Mac mini Full Screen Turns Green

Fiddling System Preferences > Accessibility > Display > Cursor size fixed the QuickTime Fullscreen error for me while in 10.14.5.

https://discussions.apple.com/thread/250421147?answerId=250808038022#250808038022

check the cables to your display. If possible check with another cable, then try another monitor.

If the problems follow the machine around it could be the graphics chip

do other full screen videos do this as well or just with you-tube?

In 10.14.5 when QuickTime or QuickLook was in full screen mode, as soon as the mouse and controls vanished the screen went completely black.

10.14.6 fixed that but in my setup (Mac mini 2018 and LG 23" Thundebolt 3 display) the screen gets a reddish cast (not big but noticeable) then instead.

As a follow up, an HP 1440p connected over Thunderbolt/Displayport works fine except some older SD Youtube videos go dark when the mouse disappears, and some HD Youtube videos go ever so slightly red when the mouse disappears. Weird.

My own videos play fine in Quicktime and TV.

Thanks for the suggested work-arounds, but they only last until a restart.

The cursor size fix also worked for me. Hands down strangest solution I’ve ever seen. In short, go into accessibility, display, then increase the size of your pointer.

Thanks for the info but it's just a workaround that is unconfigured at every restart. we need a definitive solution

Monitor make & model?

Monitor make & model?

This just started happening on my Mac mini (Late 2014) over the last couple of weeks. Happens when plugged in to my Panasonic 1080p TV and my Dell 1440p monitor (both over HDMI).

Go to System Preferences > Displays > then select Scaled option and change the resolution.

This is the crazy- but it works. I had to make my cursor quit a bit bigger but it sorted it out. Thanks!

Thanks, this did work for me for whatever strange reason. Also as someone pointed out, you can change the size of the cursor back and it will still work.