Picked up a touch screen last week, having set it up there is a thin blue (cyan?) line on it.
I've tried the screen on two Pi's with the same result.
Line is present running cli or desktop
line does not change position when I use lcd_rotate=2 and reboot.
Before I contact the supplier and get a replacement I wanted to ask if anyone had seen this before.
I've changed the desktop colour in the pic below as it didn't show up clearly with the default colour.
(Edit to fix image links)