Mods Installed:
Fabric API 0.96.11
Immersive Portals 5.1.7
Indium 1.0.31
Iris Shaders 1.6.17
Lithium 0.12.1
Mod Menu 9.2.0
Sodium 0.5.8
Chisels And Bits 1.4.156

Blocks turn invisible after chiseling with Immersive Portals installed. I am running version 1.20.4 on fabric with the mods listed above. I have tested this without the Immersive Portals mod, and it works, until I install it again.

Same here

Specifically, this occurs when a portal is placed down nearby, if none are within render distance, or are not visible (e.g. hidden portals) the issue does not occur.

Any updates on this?

I have the same problem but even in a fresh world without portals it still breaks giving ghost blocks. An update fixing this would be appreciated, especially as these mods would be a great combination to have for a variety of reasons.