Text frames become almost invisible when "Size follows 'Stave space' setting" is UNchecked

When ANY text with a frame around it, such as a rehearsal mark, has the "Size follows 'Stave space' setting" option ☑checked, the frame displays as normal, no problem:

However, when the same option is ☐UNchecked, the frame becomes so thin it is almost invisible:

I am not sure if this affects the printed score when printed, or if this is just a visual glitch.