Quick filter regex with anchor and alternation

I want a quick filter for files that begin with arbitrary characters like "abc" or "xyz". I tried
Set QUICKFILTER=regex:^(abc|xyz)

That filtered out everything even the files that matched the patter

Try adding .* to the end.

Behaved the same with .*
screenshots

Set QUICKFILTERFLAGS=regexpon
Set QUICKFILTER="^(abc|xyz).*"

Works in my tests.

Yes yours works, thank you

You can set both things at once as well:

Set QUICKFILTERFLAGS=regexpon QUICKFILTER="^(abc|xyz).*"

(Might make a difference in a directory with a lot of files.)

I tried:
QUICKFILTERFLAGS=regexpon QUICKFILTER="^(abc|xyz).*"

and got error
https://imgur.com/a/I9j9a5W

You forgot the leading Set.