First use of an acronym with \acp with acro package shows strange result [closed]

Question

I have problems with the \acp from the acro package.

Here an minimal example:

\documentclass[]{article}
\usepackage{acro}
\DeclareAcronym{MP}{
        short = {MP},
        long = {Member of Parliament},
        long-plural-form = {Members of Parliament}
}
\begin{document}
\acp{MP}
\end{document}

It shows $\Delta$ (MPs) (latex notation) as result instead of Members of Parliament (MPs).

Answer 1

The problem was solved by an update to recent acro version (2.2b).