Negative lookbehind not working?

Hi again,

I'm trying to match date string. I use https://regex101.com/ with 'Flavor' set to 'PCRE' to test.
I've used Negative lookbehind to NOT match anything containing numbers prior to date.

Pattern: .*(?<![0-9])\K(\d{2,2}).(\d{2,2}).(\d{2,2})

Test string: Series61.03.04.21.Anything.at.all

This works perfectly in regex101, but matches nothing at all in Advanced Renamer.

Does anyone have any ideas?

TIA

Update, I solved my own problem by altering the first part of the string. Instead of negative lookahead (which I clearly do not yet understand).

([a-zA-Z0-9-_]+).

This captured the required input.

I'm still learning :