We had an issue a while back where if a new attachment was created/added with the same file name as a previous attachment, then the file would be overwrittten and all previous attachments would show the new file. We thought this was fixed in 2018 (by the Task ID being added to the file name of the attachment) however it seems not to be the case. Sometimes the Task ID gets added, but often not (See attachment)
Why is this behaviour inconsistent?