1. Open the editor and go to Edit->Edtior Preferences.
2. Select Keyboard Shortcuts.
3. Go to Play World and change Resume to F5 and Step to F10.
4. Run with a breakpoint in a blueprint that you can hit easily.
5. When you hit the breakpoint try to use F5 or F10, neither will work.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-9771 in the post.