Regexextract not working with non-capturing groups or with lookahead/lookbehind

Hi here,

I have strings with variable length and I need to extract a certain pattern into a custom column.

Sample string (I need the digits after the last underscore):
Output would be: 105335

A regex that works at

But this does not work at Metabase on a custom field.
I've also tried regex lookahead and lookbehind but those dont work either.

Any ideas?