After asking the app to move the sync folder, the folder disappeared from the old drive "250Gb/Idrive-Sync" and was created in new location "Photos/Idrive-Sync" with files in tact.
BUT the application showed the sync folder location as a different volume "Photos-1/Idrive-Sync.
If I ask the app to open the sync folder it opens an empty folder on the phantom volume "Photos-1".
When I turn on sync it begins to download the whole online copy back onto the local machine (so I would end up with 2 copies).
Can't make the app recognise the new "Photos/Idrive-Sync" folder as the new sunc folder.
Last option: How do I reset the app so that it forgets past sync locations and allows me to start again ?
(If I disconnect and reconnect, it still remembers the old data)