EP500 Offline UPS behave like same as Online UPS mode

A background: I have been running my EP500 in Customized UPS with Standard UPS set in Offline mode. When grid AC is present, it power passthrough to the load AC Output port. This operation failed about 2 weeks now. It acts just like it in Online mode which the grid AC supplies to the EP500 then the battery supplies power to the load Output port. The problem is my load requires the full grid AC 12A (1300W). But the EP500 only draw 540W from the grid. So, the battery drains really fast. Does anyone who owns EP500 has this problem?

@randychan38 EP500 has a built-in adapter with a maximum grid input of 600w.
If the load exceeds 600w, the machine will also be discharged together with the load.

Thank you for your info.
After I posted to this community. I have also sent an inquiry to Bluetti Service team. This issue has now been fixed after working with the Service team.

For recap in case someone may run into this. I originally was working on a different issue. In the process, I changed the Max. Grid Input Current from 14A to 12A. This Grid Passthrough failure happened 3 or 4 days later as the load requires higher than 12A power. I forgot about I have changed the setting. After working with Bluetti Service team. Discovered the cause of failure was done by me. It is fixed now changing the setting back. Many thanks to Bluetti team, Admin, and Jermen.