Normally the script works even for unnamed segments.
Just for test:
1) create some new segments and let them "red"
2) select them and script->properties
3) change city name only
=> works (for me)
IMO, It is more probably the payload (number of changes to send to the server) which lead in error.
Some users, during the test phase, reported me same problems and after another try having the correct behavior without any change.
I also have same problems sometimes with JNF and after 2 or 3 retries, it works...
Nevertheless, I will perform again some tests.
Nope, that is a different thing. If there are too many changes, there may be timeouts, "segment already changed", ghost segments, etc, but that's not the case here.
I've just tested a simpler version. Picked two segments, one with name one without. Properties->set name->save failed.
I'll say again, this is a bug introduced with the new editor and is happening with the original ext tools and this new tools, so to solve it one needs to understand what changed on the new editor.
Here's an example which you most probably can't edit but will show you the real case with two segments, one with and one without name link
Edit: definitively a case of empty name, I'll ping you directly.