When I last used affinity designer I could move a text box until it lined up with the edges of radius corners shown in the image below and the text box would snap to them, this is no longer the case. My snapping options have not changed but I have tried various combinations to get it working again without luck. I frequently use this to lay out text and have numerous documents where this will no longer work.
I've not used Designer for a couple of months So I cannot say for certain if the 1.9 update is responsible or not, unfortunatly I updated to 1.9 before noticing this issue. It was however working fine when I last used it and I have not changed any other settings in the meantime, quite literally stopped using it and picked it back up again. I'm experiencing the same issue on both my laptop and desktop windows computers.