A multi should be in external control, that is the correct state for an ESS system.
There isn't enough info here to troubleshoot it.
https://www.victronenergy.com/live/battery_compatibility:freedomwon
Follow this link, and step through every item and make sure your system is properly configured as documented.
Send your DVCC settings, pull the BMS limits CCL, CVL, DCL chart in VRM, and also cell min/max.
You need to understand if the voltage limit is being enforced by the battery for some reason, imbalance etc.
50 People are following this question.