Not sure why you think I've got 4.2.2 - I can assure you I have 4.2.3 and it was this upgrade that caused the problem until upgrading it was fine.
I want to revert back but I don't have a copy as I just moved to a new computer
It seems clear to me that the issue is that WP doesn't have enough options when selecting 'background image position' and only allows 'center' positioning and suffusion which allows 'bottom center' isn't overriding WP selection.
Is there a workaround until a new version of suffusion comes out that can combat this please?
Anyone else for any suggestions?