I have had a strange issue reported by one of our departments.
Currently they place A4 Letterhead print side down (back of paper facing you) within Tray 1.
I have been told that as of yesterday for some users the printer is printing on the reverse of the letterhead (non printed side) and for others it is printing on the correct side of the letterhead, then randomly it will revert back to printing on the correct side for no reason.
Hope that makes sense and if so any advice appreciated.
This was an issue in a few firmwares, but it certainly wasn't random, what it was , was this.
If you printed 1 sided it would print on the wrong side of letterhead/labels, if you printed duplex all was right with the world (Or vice - versa, I honestly can't remember which)