On August 28, 2021 at 17:55, james_aa said...
Update - I got this sorted it was just an edid issue.
What’s weird is on previous versions of ATVs they would give you resolution options even if you couldn’t support them but now they seem to run some sort of check and only show what’s available, my matrix was giving the wrong edid info hence the issue
Don't you just love HDMI?