unfourtunatly (or fortunately??) Deleted the app, then reinstalled. This resulted I a loss of my files, which is had not backed up to iCloud... then I ended up doing a restore on my iPad to before I did the iOS upgrade and reinstalled affinity and my files and now the problem is not showing, the filter and effects layers are working properly again. It is a good news/bad news story. Thank you for offering to help.
if the problem crops up again I will do a video of the behaviour as you suggested.