Is it a mod compatibility issue?

Yes

Minecraft version

1.19.4

Describe the issue

.

Seconded. Kinda rough that Immersive Portals has the EXACT Sodium/Iris versions listed as a Required dependency, as opposed to either loosening up the range or making it Optional.

Same, only time I got this to work, is via using 2.6.4, and a very specific version of sodium... but then I can't use another mod because now sodium is "outdated".

@SeymourGx I have to clarify that being compatible with only one Sodium version is not Immersive Portals' fault. To make portal rendering work, ImmPtl must deeply change Sodium rendering process, and ImmPtl uses Sodium internal API which Sodium does not keep stable.

And ImmPtl does not depend on Sodium. In nvidia videocard there is a driver bug that Sodium workarounds, which is also useful for ImmPtl. But on AMD and Intel videocard there is no such dependency.

Understandable. To clarify, I just mean the fact that when one attempts to launch ImmPtl right now with the new Sodium/Iris, it'll give a mod dependency failure and refuse to launch, due to being a Required dependency. Makes sense given how immersive ImmPtl is with graphics. Maybe making a minimum version but no maximum?
I at least saw in Sodium's new patch that they're trying to add a stable API to stop this sort of thing. Perhaps this'll be moot in the near future.

Resolved in 2.6.7