You should be able to add wss:// urls to relay lists/sets.
I'll have a look at merge, could definitely have broken something there. 🙈
wen adding of wss:// for relay lists/sets? And merge doesn't seem to work anymore (can't choose lists from dropdown). Otherwise great work. Preparing next release version of nostr:npub1gp4xzpmluelsakjtayc4wtzj97fhj5kakqjvsannu00xkdlf4x8s0xdqyq to also support most of nip51 stuff.
Discussion
You can when it's a fresh new list.
You can't when your're editing an existing list and trying to add a new element to it.