Hi Michael, many thanks for responding. I’m saving the project files to my iMac (not shared) and the media is on an external drive. I’ve done a verify then repair permissions on my drive in disk utility but it didn’t help unfortunately.
What is working is putting a sequence in each bin (just a new sequence)…then the ‘Save Bin’ option becomes available and nothing seems to be disappearing. This is solving the problem for now but I have no idea why….do you know? thanks again, Helen