It seems like GZDoom 4.6.0 doesn't load GLDEFS lumps if they're in a filter folder. I've check my code and tested my "More Lights" mod in GZDoom V4.5.0 and LZDoom and it works just fine, so I'm pretty sure this is not caused by me.
Here are the locations of the GLDEFS lumps in my PK3:
"filter\doom\GLDEFS"
"filter\heretic\GLDEFS" and so on
Screenshots:
GZDoom V4.6.0 running with the PK3
https://imgur.com/a/9cKsOXx
GZDoom V4.5.0 running the same PK3
https://imgur.com/a/eoGrwAV
The PK3 is in the attachments.
Thanks in advance!
