I’ve been able to replicate this with FontAwesome and with heading tags, where I am trying to create new “groups” of fields for a certain content type, and when I move them into said groups, they lose the customizations I had added, like default heading name, default list info, etc. It just all goes blank.
Working on a screencap, but the proof would be have an H3, configure it, then make a new div, and put the H3 into the div. It loses the title and any adjustments.
What’s crazy, though, is once it’s moved back to where it was, it regains all the info it had before!