0:521 error in SAP when switching or clicking to view another PDF document
Hi,
Would need some assistance to see what we need to check please. Currently, when we view PDF attachments on a document in SAP, the process either 1) is very slow or 2) leaves a blank screen and when switching to another PDF, error below appears - 'There is a problem with Adobe Acrobat/Reader. If it is running, please exit and try again. (0:521).

We are currently on 20284 and have tried suggestions to untick 'enable protected mode at startup' and untick 'enable enhanced security' but behaviour is still the same. Reinstalling and repair have been done as well but same issue.
