I start with posting the smallest segment of code I was able to create for reproducing this problem:
\documentclass[usenames,dvipsnames,a0paper, subcolspace = 3 mm, colspace = 3 mm, landscape, innermargin = 0 mm, margin = 0 mm, blockhorizontalspace = 5 mm, blockverticalspace = 5 mm, 25 pt]{tikzposter}
\usetheme{Envelope} % See Section 5 (Rätt okej!)
\usecolorstyle[colorPalette=BrownBlueOrange]{Germany}
\tikzposterlatexaffectionproofoff
\begin{document}
\makeatletter
\setlength{\TP@blocktop}{.495\textheight}
\makeatother
\settitle{ }
\begin{columns}
\column{0.49975}
\colorlet{blockbodybgcolor}{MidnightBlue!100}
\block[bodyoffsetx = 0 mm, bodyoffsety=-2cm,bodyverticalshift = 0 mm,bodyinnersep = 3 mm,titleinnersep = 0em,roundedcorners=0]{}{\color{white} \fontsize{80pt}{80pt}\selectfont \flushleft \bf{Main question? \\ \fontsize{60pt}{60pt}\selectfont \begin{description}
\item[ $\bullet$] Bullet 1 description
\item[ $\bullet$] Bullet 2 description
\begin{itemize}
\item Bullet 1 itemize
\item Bullet 2 itemize
\colorlet{blockbodybgcolor}{white!60}
\end{columns}
\end{document}
And the resulting figure:
There you can see that using the "normal" bullet list approach, the bullets will begin before/outside the beginning of the block.
I dound a trick to go around it, with desrciptive list and \item[ $\bullet$]. That is however a "cheap solution" and should not have to be like that.
Any suggestions what I did wrong in the first place?
Thanks on advance!

bodyinnersep = 0 mmthe content of a box comes immediately at the border of the box. So it might not be a good idea, as I see it. – Lars Abrahamsson Jul 25 '18 at 22:38titleinnersep = 0emis that I do not like the titles of the boxes included in this packade. I want to design my boxes myself. Maybe it was the wrong way of doint it? – Lars Abrahamsson Jul 25 '18 at 22:40\end{itemize} \end{description} }}. One closing brace is for the\bf{, one for the\block{. So I don't get any output from your code. Unrelated:\bfhas been deprecate for 25 years, and it's not a command that takes an argument, but a switch that affects the following text in the same group. That is, you should use\bfseriesinstead, and it's used as{\bfseries ...}. – Torbjørn T. Jul 30 '18 at 11:04