Hello, i recently updated my LibreElec build to 8.00 (Kodi Krypton). The remote over HDMI feature works, but my TV will no longer wake when i turn on the PI.
Judging on Your initial post - that functionality was working fine prior to upgrade.
Nevertheless, it is always good thing to check current settings on Your TV as well. So, check if there is an option in Your TV to enable such behavior. Then try with different HDMI port on TV, ...