Notes not being correctly transferred from PC to IPAD

Hello Adobe community!

I have a PDF which has some notes added from beforehand. 

The problem is that all the notes are visible on my desktop(HP, windows 10). However when I try to view the notes on my IPad(Air 3, latest IPadOS) it shows weird characters like 'ypb' or 'ypm' etc.

I can see that there is a note present but on opening it the content is missing and instead replaced by these characters. This is the case for approx 80-90% of the notes. Very few are visible. 

Would appreciate any help on how to solve this problem. 

Thanks