\cline is not drawing the line

Question

In the table:

\begin{table}[h]
\hfill
\begin{tabular}[t]{l|c|l|c|c|}
\cline{2-5}
Zestawienie VAT: & \cellcolor[HTML]{C0C0C0}\textbf{\begin{tabular}[c]{@{}c@{}}Wartość\\ netto {[}zł{]}\end{tabular}} & \multicolumn{1}{c|}{\cellcolor[HTML]{C0C0C0}\textbf{\begin{tabular}[c]{@{}c@{}}Stawka\\ VAT\end{tabular}}} & \cellcolor[HTML]{C0C0C0}\textbf{\begin{tabular}[c]{@{}c@{}}Wartość\\ VAT {[}zł{]}\end{tabular}} & \cellcolor[HTML]{C0C0C0}\textbf{\begin{tabular}[c]{@{}c@{}}Wartość\\ brutto {[}zł{]}\end{tabular}} \\ \cline{2-5} 
                 & \multicolumn{1}{r|}{}                                                                             & zw                                                                                                         & \multicolumn{1}{r|}{0,00}                                                                       & \multicolumn{1}{r|}{}                                                                              \\ \cline{2-5} 
\end{tabular}
\end{table}

The top line is not drawed by the \cline{2-5}. What could be the issue?

EDIT: The code with removed other user content is here. Unfortunately when I try to compile it, I get some error, which can't solve easily, but in the end the pdf is working and the table without top line is generated. I use the \usepakage[table]{xcolor} package mentioned by @daleif in the comment:

\documentclass[a4paper,pagenumber=no,9pt,DIV=10]{scrlttr2}
\usepackage[polish]{babel}
\usepackage[utf8]{luainputenc} 
\usepackage{invoice}
\usepackage[table,xcdraw]{xcolor}
\usepackage{graphicx}
\addtolength{\textwidth}{2.5cm}
\addtolength{\hoffset}{-1.25cm}
\addtolength{\voffset}{-1.25cm}
\usepackage{fontspec}
\setmainfont{Calibri}
\usepackage[parfill]{parskip}
\def\mydate{\leavevmode\hbox{\the\year-\twodigits\month-\twodigits\day}}
\def\twodigits#1{\ifnum#1<10 0\fi\the#1}
\usepackage{pgfkeys,pgfcalendar}
\usepackage{booktabs,caption,float}
\usepackage{newfloat}
\DeclareFloatingEnvironment[fileext=lot]{table}
\usepackage[export]{adjustbox}
\usepackage{amsmath}
\newcount\julianday
\newcount\daycount
\newcount\weekday
\newcommand*{\adddays}[2]{%
  \pgfcalendardatetojulian{#1}{\julianday}%
  \daycount=#2\relax
  \loop
    \advance\julianday by 1\relax
    \advance\daycount by -1\relax
  \ifnum\daycount > 0
  \repeat
  \pgfcalendarjuliantodate{\julianday}{\thisyear}{\thismonth}{\thisday}%
  \thisyear-\thismonth-\thisday
}
\begin{document}
\begin{table}[h]
\hfill
\begin{tabular}{lrlrr}
\cline{2-5}
\multicolumn{1}{r|}{Zestawienie VAT:} & \multicolumn{1}{c|}{\cellcolor[HTML]{C0C0C0}\textbf{\begin{tabular}[c]{@{}c@{}}Wartość\ netto {[}zł{]}\end{tabular}}} & \multicolumn{1}{c|}{\cellcolor[HTML]{C0C0C0}\textbf{\begin{tabular}[c]{@{}c@{}}Stawka\ VAT\end{tabular}}} & \multicolumn{1}{c|}{\cellcolor[HTML]{C0C0C0}\textbf{\begin{tabular}[c]{@{}c@{}}Wartość\ VAT {[}zł{]}\end{tabular}}} & \multicolumn{1}{c|}{\cellcolor[HTML]{C0C0C0}\textbf{\begin{tabular}[c]{@{}c@{}}Wartość\ brutto {[}zł{]}\end{tabular}}} \ \cline{2-5} 
\multicolumn{1}{l|}{}                 & \multicolumn{1}{r|}{500}                                                                                                  & \multicolumn{1}{l|}{zw}                                                                                    & \multicolumn{1}{r|}{0,00}                                                                                            & \multicolumn{1}{r|}{500}                                                                                                   \ \cline{2-5} 
                                      & \multicolumn{1}{l}{}                                                                                                   &                                                                                                            & \multicolumn{1}{l}{}                                                                                                 & \multicolumn{1}{l}{}                                                                                                    \ \cline{2-5} 
\multicolumn{1}{r|}{Razem:}           & \multicolumn{1}{r|}{500}}                                                                                                  & \multicolumn{1}{l|}{-}                                                                                     & \multicolumn{1}{r|}{0,00}                                                                                            & \multicolumn{1}{r|}{500}                                                                                                   \ \cline{2-5} 
\end{tabular}
\end{table}
\end{document}

Answer 1

The text Zestawienie VAT: has no semantic reason to be in the tabular. The OP has probably created a column for this text because if wants that text aligned with the first row of his tabular. But it's not possible to set the baseline of the tabular on the first row because of the first \hline (and the use \firsthline of array doesn't help because the first row has not a standard height).

That's why the OP has tried to put Zestawienie VAT: in a first column of the tabular. Doing so, he has to use \cline instead of hline. However, \cline is not compatible with \cellcolor (because the rule drawn by \cline protrudes in the following row and is covered by the colored panel drawn after the rule; remark that this is for only historical reasons: \hline has not that behaviour).

In order to solve that problem, I suggest to use {NiceTabular} of nicematrix. The rules are drawn with PGF/Tikz and there is no problem to have a baseline of the tabular on the first row (and there is no problem to put Zestawienie VAT: before the tabular).

\documentclass{article}
\usepackage{xcolor}
\usepackage{nicematrix}
\begin{document}
\begin{table}[h]
\hfill
Zestawienie VAT: 
\begin{NiceTabular}[t]{clcc}[hvlines]
\CodeBefore
  \rowcolor[HTML]{C0C0C0}{1}
\Body
    \Block{}{Wartość\ netto {[}zł{]}}
  & \Block{}{Stawka\ VAT}
  & \Block{}{Wartość\ VAT {[}zł{]}}
  & \Block{}{Wartość\ brutto {[}zł{]}} \ 
  25123,89 & zw & \multicolumn{1}{r}{0,00} & 25123,89 \ 
\end{NiceTabular}
\end{table}
\end{document}

However, several compilations are required.

Answer 2

Works well -remove the tabulars inside and the \multicolumn -- its not required

\begin{table}[h]
    \hfill
    \begin{tabular}[t]{l|c|l|c|c|}
        \cline{2-5}
        Zestawienie VAT: & 
            \textbf{A} & 
                \textbf{B} & 
                    \textbf{C} & 
                        \textbf{D} \\ \cline{2-5} 
        & \multicolumn{1}{r|}{}                                                                             & zw                                                                                                         & \multicolumn{1}{r|}{0,00}                                                                       & \multicolumn{1}{r|}{}                                                                              \\ \cline{2-5} 
    \end{tabular}
\end{table}