@James Ainsworth Think I maybe need to add a bit of additional context here.
As you have seen, we use 'Suspend' to manage the time (in our case 2 working days) before the BPM progresses to the next stage if it doesn't receive an email update (any email update progresses the request). The issue for us appears to be that the suspend is never expiring when no update is received, therefore the call remains permanently stuck at the 'Wait for off hold' stage when it should actually progress to the next stage, which is to send a further reminder email to an authoriser (specified by a custom field in the original capture) and again suspend for 16 hours. After this if a response still isn't received, it should progress to a closed state as not authorised. If at any stage an email is received updating the call, it will progress.
This has always worked fine since implementation over 3 years ago, until after 19 July when it seems to have stopped. I believe this corresponds with 'Service Manager' update that seemed to cause various issues for several customers. As Archana has stated, we haven't changed anything it just stopped working after this date.
I wonder, is it possibly linked to this?