Coreelec can be transfered from a SD/USB card to emmc very easily using the ceemmc tool.
SSH into the box and simply enter the command ceemmc and it will do everything automatically. It is well tested on the VIM’s and has never failed to work for me.
The VIM’s are one of the main test platforms for the Coreelec project so its very unlikely that your issues are related specifically to the release 9.2.2 as no version is released without first passing testing on the VIM’s.
Get a bootable SD and test all is working OK and then issue the ceemmc command from SSH when you have assured yourself its OK.
In my experience when you encounter a problem with playback after a major upgrade (jumping from 9.2 to 9.2.2 is a major upgrade which has skipped a full version) its usually a problem of retained settings messing up the operation of the new version. In this case a fresh install from scratch usually resolves all issues. Start with no addons and reload them one by one testing that all is OK after each one. Addons are the major source of system problems and only the official Kodi or CE ones are guaranteed not to cause instability.