I have been using the First Admin Theme plugin for a long time. It worked for ME very well. This week there was a GForm update and I ran into a bug. Basically when the First Admin Theme plugin is active the scroll bar to create the form with GForm disappears.
Check this video https://www.loom.com/share/a6cb51e4b42746fe86c8ab8b15dc5777
I replicated this problem on other sites where I have the latest version of admin first theme installed