I saw that this was a problem that was closed last year, but there was nothing in the thread to help troubleshoot this. This problem exists in my modpack as well as an installation with Atomic Science as the only mod. Thank you!

Redownloaded forge 1.12.2 - 14.23.5.2846 and it fixed it. Still can't figure out why the other installation won't work.
EDIT: the mod "appliedenergistics2-rv6-stable-7" causes this issue. That's the latest release of Applied Energistics.

Interesting that AE2 would cause this, try with the latest alpha of Atomic Science as I think we fixed this a while back. https://www.curseforge.com/minecraft/mc-mods/atomic-science/files/all