Since moving to Thunderbird 78 I have found that I am unable to 'Detach' or 'Delete' some [jpeg] attachments from emails. When doing so, it goes through the usual actions including the message that "this cannot be undone" but does not do so. Prior to this version it all worked as expected. I have run though vacuous diagnostic tests (safe mode etc.,) but to no avail. I would therefore be grateful for some assistance. Many thanks