When I create a nether immersive portal the Nether Portal Spread mod doesn't recognize it, doesn't send a message about a portal being created, nor it spreads.

It was patched in an old Forge version, but they don't seem to work together in updated Fabric version.

I have the same. Not tried Forge, but on Fabric the issue that was fixed in Forge is still present.

I could have sworn I've seen a pack with both mods working but now I can't remember where it was. I'll try to update here if I can find it and see if they made their own data pack or something.