This probably also affects datapacks.

Definitely caused by lines 62-71 in ModResourcePackUtil.java. Not sure of the side effects of removing.

Happens on Fabric too, seems to be an issue there

I have the same issue, for me it's only happening on quilt, not on fabric (tried on 1.20.4)

This is fixed in 1.21.1+ (when released), and probably wont be ported back to earlier versions.

This is fixed in 1.21.1+ (when released), and probably wont be ported back to earlier versions.

So, that's it, then? No one's going back-port this? People still using 1.20.4 are just stuck with a big, ugly pile of mods in their Resource Pack lists? And what about how this disables the ability to save Resource Pack setups in that specific version? That's kind of a problem!

I genuinely feel that the answer of "fixed in next version, issue closed" isn't good enough. You allow users to install newer versions of the loader on numerous versions of Minecraft. If this is something you can fix on your end, then why not fix it for the specific afflicted version, 1.20.4, instead of moving along?

Your post indicates that it's possible. If this is Mojang's fault, instead, and it's nothing you can fix for this specific version, or of it would be too much of a pain in the butt to bother with, then fine. Just say so. But as it is, dusting your hands and looking ahead to the future like a pretty lame way to deal with a problem that still exists for people using older clients.

That's how I see it, anyway…

The problem exists due to a lack of my own time to dedicate to this project. Because of this, if I am able to fix it in a future version, that is great, but I already struggle keeping up with the latest version. How am I supposed to support many previous versions as well. I understand your frustration, but there is only so much I can do.

Ah, well that's different! It's also perfectly reasonable.

Thank you for taking the time to explain, and I apologize for my somewhat aggressive post. In the grand scheme, this really is a tiny thing that probably won't be relevant in the near-future. It just happened to be relevant to me at this specific time.

Life is weird like that…