Hi all,
I was able to reproduce this in 4.7.3 and in our main internal build. It looks like attempting PIE at any point while Auto Recompile Blueprints is disabled generates this error message. My guess is that errors you get when not compiling are from other Blueprints, and it’s unrelated to PROTO BP compile bug. I’ve entered a bug report for issue (UE-12038), and I mentioned that you received several errors when choosing not to compile these. I’ll let you know as soon as I see an update on issue. Thanks for your report!