Thank you for looking into it, Chris.
I found a way around - not very convenient, but it is okay if there is no text and layer blending. I did save files to PSD, which can be opened in the previous version of Affinity.
I understand that Affinity team is not responsible for a bug on wacom´s side, but in the end, for me as an user the previous version allows me to work more smoothly. So I will rollback for now and contact Wacom´s forums in hope that they can fix the issue. I would like to help with the freezing issue, but I also wasn´t able to notice, how to reproduce it.
But I only have observed this - in 1.7.3 (or 1.7.+) when the focus problem with brush tool accured, it also froze the transformation tool. In 1.8. the tranformation freeze seems to occur independently on the brush tool problem, and also when I am staying within the app, without changing focus. It happened to me very often when I was adding photos to the scene, or copying existing layers and working with them, I would say that even as often as every 2-5 minutes. Although there probably is some pattern, it just seem to happen on random and I do not know what the steps to reproduce it could be.