QA checker does not seem to work with simple regex

Hi,
I'm trying to raise an error whenever an English cell ends with "(%)" and the target cell does not end with such pattern. To do so, I wrote the following regexes:

For source:  \(%\)$
For target: [a-z0-9]$

I made sure that the "case indifference" box was checked.


QA does not raise an error, which is surprising given that I'm perfectly able to 'manually' achieve this QA but using the following detour:

1-filter  the source using 1st regex,
2- ctrl+ f in target to find the cells where the percentage is missing.

Why don't the regexes work in QA?

Thanks.