Forge version: 35.1.28
Futurepack version: 21.0.4

I think I recall Prismid generating on the surface in the Deadlands on Tyros.

I have looked around a lot in this version, but have not found any. Might be a bug, or might be I'm looking in the wrong place.

it genrated as ore, I added another layer at the top so its more visible again.

Hm, I also looked underground in 21.0.4 without finding any Prismid, but perhaps it was just very rare.

Solved in DEV sounds like a new version; any estimate of when it will be available?

You can play DEV version now and try to find some bugs to report.
https://www.mediafire.com/file/mmmrw65ckdc34xn/Futurepack-1.16.4-21.0.4.jar/file