renaming the struct worked for me. however, in my case, i wasn’t changing any default value or variable type. i was adding members to the struct which broke the pins on editor restart, so might be a different bug. editor version 4.12.5.
also note, i haven’t been able to reproduce this on a clean project, and in all cases where the pins broke on the existing project involved a blueprint forloop. recreating these nodes didn’t solve the problem. the only successful workaround so far has been struct renaming.