It works on my copy of mIRC 7.52
Don't really know what to tell you.

Try this.
Code:
; /findall sometext
findall {
  var %src = $active, %win = @findall, %pattern = $(*,$1-,*)
  window -e %win
  filter -ww %src %win %pattern
  echo -tic notice %win --- Found $filtered matches in %src for %pattern $+ .
} ; by Raccoon 2018

Well. At least I won lunch.
Good philosophy, see good in bad, I like!