Minecraft version: 1.16.1
Forge version: 32.0.108
Botania-1.16-402

When looking at the Runic Altar with a recipe, all the blocks around becomes invisible. You can still see fluids.

Proof

Do you happen to also be using the Immersive Portals (Forge) mod? I didn't notice this issue until I started using it, and the issue goes away if I remove that mod.

This has been around for some time. As far as I've ever seen it, it's 100% related to the Immersive Portals mod, as DGilbert23 mentioned. Check out #3237, which has been closed (due to inactivity), but is still relevant.

This issue is stale because it has been open for a while with no activity. Remove stale label or comment or this will be closed soon.