So I’m using JabRef 5.0 and so far it is working great. I’m very happy that you guys fixed the groups. Anyways, I have one issue and one suggestion. The issue is quitting. Every time I quit JabRef (Mac OSX High Sierra) it freezes. So a force quitting is the only alternative (it also happens sometimes when very large groups are created, but I also have a library of 5000+ entries). My suggestion is that, in order to encourage the use of keywords (and thus, of groups), it could perhaps be available in the “Required fields”.
Anyways, I’m really really happy with the new version of JabRef. Keep up the good work!
Best to all