I might try:
1. The last firmware offered at the LG site.
2. Do a factory reset.
3. Try a new HDMI cable (try cheap ones from "AmazonBasics".)
4. Try the old HDMI reset tech trick.
a. unplug one end of each HDMI cable.
b. Remove power from HDMI devices.
c. Wait 10 minutes.
d. Connect and test.