NOTE: This extension at the time of writing will cause used within SMW semantic search to be removed from your query as it will be considered a declaration of the page category rather than a condition. I am sure this will be fixed.
Topic on Extension talk:MsCatSelect
fixed?
Still not fixed, but you can patch the extension to make it work with #ask:
In the file MsCatSelect.php
modify the pattern declaration (line 74)
replace
$pattern = "\[\[({$categoryNamespace}):([^\|\]]*)(\|[^\|\]]*)?\]\]";
with
$pattern = "(?<!#ask:)\[\[({$categoryNamespace}):([^\|\]]*)(\|[^\|\]]*)?\]\]";
This way the extension skips all category patterns directly preceded with #ask:
Hi! I just merged your patch in version 8.1 (diff). However, note that it only works when the category link is right after the #ask, so it's more like a hack than a fix. Doing it robustly would require advanced wikitext parsing. Cheers!