“Charger Only” mode will continue providing AC power to your outlets; “charger only” just means that it won’t automatically switch to inverting when it loses incoming shore power. Passthrough from available shore power is unaffected… so double-check the position of the 3-position switch on your MultiPlus to be sure it’s in position I and not position II.
Failing to read the incoming shore power, though, is almost certainly a “stuck” current sense port - your AC Input is working, else you couldn’t be charging, but the Multi isn’t registering it because its current sense port is stuck closed and it’s looking for data from a nonexistent external current sensor.
Here’s the Victron document describing the issue as well as the fix:
2021-12-mpii-esii-quaii-current-sense-socket-issue.pdf (427.8 KB)