This may not be a kodi problem but i thought i would post it anyway.
I have been playing mkv movies though a firestick for years with minimal problems. I swapped with a fire cube 3 and it seems any movies with dts have the video a half to one second or so behind the audio. At first i thought it may be an hdmi issue so i replaced the cable with a fiber optic hdmi to my epson 5050ub projector. Didnt help. Tried my old projector trying to eliminate causes and no help.
It only happens in kodi and playing movies stored on my nas, netflix and other apps dont have the issue, of course i they arent streaming dts as far as i know.
Then for the heck of it i swapped the cube for a firestick 4k max hooked to the same hdmi input to my marantz rcvr and problem was gone. It only happens on the cube. I tried uninstalling kodi on the cube and reinstalling. No help. I made sure both devices have the exact same settings on devices and kodi. I can select the cube, play a movie and it has the delay and switch to the 4k max and play the same file and it plays perfectly. I guess i can just use the firestick but i would really like to figure out what the issue is with the cube and kodi?
Yes i have update both devices. True HD videos play fine on the cube. Just weird!