Affinity Publisher Beta 1.7.0 on MacOS Mohave 10.14
Had been editing existing frame text and afterwards eventually found that the blue selection border was displaying regardless of what I did.
Selecting other things or selecting/unselecting the frame text object does not help.
Selecting a different layer does not help.
Toggling UI does not help.
Quitting the app and re-opening the Publisher file does not help.
The only way I can get rid of the selection border is to turn the layer off, but it returns when I turn the layer back on. The border does not print; it's just distracting. I have not had this problem with any other file or frame text.