PDF crashing when marking up

Hi there,

I have an iPad Pro running iOS 17.2. I have a large number of pdfs stored in iCloud which I mark up (highlight / annotate) using the Files app and Apple Pencil.

The pdfs will periodically “flash”, which causes me to lose my most recent mark-up.

Also, since the most recent update, whenever this happens the pen defaults to black felt pen (even though the pen shown as in use is the highlighter).

Please can anyone tell me how I can fix this as it is making the app almost unusable?

Many thanks,