Wise words ....

Terrific, thank you @Mez_BCNA .... but the REALLY weird thing is, thinking back, that it DOES upload the pic initially & it is fine for a number of days (or longer) and only 'then' goes 'cracked'!     So WEIRD!

So - perhaps - if you want to share a pic from the internet (particularly Facebook) maybe do a screenshot of it and save it as a JPEG (screenshots are usually PNGs and not always compatible elsewhere) and there should be no reference back to the FB post ...... 

I had been doing 'save as' for the FB pic to a separate folder & then adding it here - but some (not all) still 'cracked' & disappeared!    Double weird!

or just do as Vanilla suggests - just drag them across, cos using the 'photo icon' to add it from your own folder - doesn't always appear to work either! grrrr Bloody Technology!