[FoxForceFive]

Can you try this.

Set your Kodi display resolution to 1080p 59.94.

When I play a 1080p file it changes to 1080/24

When I play a 4k file it changes to 3840 X 2160p.

I believe the correct setting is to set Kodi to 1080p resolution.

I have nothing whitelisted.

If i set the Kodi resolution to 3840 x 2160p it does not switch to 1080p/24.

I have left GUI resolution at auto.

I don't understand why you have had to set it to unlimited.

If it says hdmi 3840x2160p when I play the 4k file and then when I stop the file it shows 1080p are you saying it's not playing in 4k?

I also read you should set the Audio output of the firestick to stereo in settings to fix audio out of sync. Is that correct?

What frame rate is the 4k file?

I know that sounds daft, but 60hz 4k files switch fine for me regardless of the gui resolution limit, but 24hz files (films for example), don't.

I set the gui resolution limit after reading the log & seeing the code look to set that resolution after finding the correct one.

Have a look at the debug logs on the bug report or the comments afterwards by the team & you can see the resolution changing back to default.

They have found a fix for it though, apparently they had a similar issue on the amlogic boxes & they can use the same fix to sort it.

EDIT: just thought, this could be an issue if you've used the whitelist at all, which I obv had done. If it has never been used it may not suffer the same issue.