I have LibreELEC 10 beta running on my Raspberry Pi 4b (4GB). I'm running the latest Nightly every day.
I have a couple of 4K UHD rips on my NAS which I playback on my Optoma 4k UHD35 beamer.
Several video's output differently on screen, while the Kodi UI is calibrated perfectly.
Some video's need a positive zoom and some video's need a negative zoom to fill the projection screen edge to edge.
I apologize for my n00b description but I guess you'll get what I'm saying.
How is this possible? Why aren't the video's filling the screen correctly? Any idea's?