It’s possible that it is a UE bug but that depends on the case and how your project is set up.
There is currently a bug report in that mentions not being able to save if the class the blueprint is based off of was edited and then a hot reload occurs. This is a specific case however and doesn’t happen in all situations.
If you do have a 100% reproduction case for this issue however, it would be very helpful if you could provide that so that we could make a solid bug report for the issue. This would require recreating the problem from a fresh project so that we know that it isn’t project specific.