Hi Martin
I tried it in safe mode with all preferences disabled but still the same result.
Another issue has also raised its head (in both safe mode and normal)
The display of insert items in channel settings has become corrupted so that there is no edit or bypass buttons.
At this point I have had to go back to using 10.0.30 instead of 10.5.20 as it is currently unusable for me in its current state.