bibcheck not working

Question

I tried to filter my bibliography in line with what I read on this answer. MWE:

\documentclass{article}
\usepackage[                  % for biblatex
    backend = biber,
    sorting = none, 
    defernumbers,
    style = numeric-comp %ieee
           ]{biblatex} 
\defbibcheck{latents}{\iffieldequalstr{groups}{Latent}{}{\skipentry}}
\addbibresource{refs.bib}
\begin{document}
\cite{foo}
\printbibliography[check=latents]
\end{document}

refs.bib:

@online{foo,
  title = {A thing},
  author = {Me},
  date = {2021-12},
  groups = {Latent}
}

Error: Empty bibliography on input line 18.

I assume this is because the "groups" field isn't really a thing BibTex recognizes. I can get around it with

\DeclareSourcemap{
  \maps[datatype=bibtex]{
    \map{
      \step[fieldsource=groups, final]
      \step[fieldset=keywords, origfieldval]
    }
  }
}

And just filtering by keyword in the normal way, but is there a solution that doesn't require me to mess with keywords?