UPS seemingly turn off during square wave inverter switchover

[wstar123]

So I encountered a new issue. The Back-UPS ES 700Y-IND when connected to a square wave inverter & a power cut happens it just simply "turn off" with usb connection still active with a momentary connection loss & a continuously flashing red led with no tone. The surge protector outlet which does not supply battery power continues to work but the usual battery backup outlets stop supplying power until I press the power switch to "reset" the ups after which it start working as usual. I already set the voltage sensitivity to "low" so once on inverter power it works as usual too after the ups is reset by pressing power switch. My question is, why it just turn off instead of switching to battery power during switchover when it can work fine on same inverter power afterwards. I have another cheap generic ups connected to same square wave inverter on another outlet & during power cut/switchover it switches to battery power for few seconds but not APC ups with supposedly much better specs.

[Teken]

If the unit is connected to a computer running PCPE / PCSS software. Indicate what the logs say and the active fault / error codes are.

Upload that information here to the APC Forum for review.

Also, do you ever see the building wiring fault (LED) or error presented in PCPE / PCSS software?

[wstar123]

Found out there is no separate log location for PCPE software & instead it is all recorded under windows event viewer. Connected the ups to square wave inverter powered outlet & during power cut no event was recorded in logs as if ups completely went dead during those few milliseconds. Tried manual power on/off the wall outlet plug powered by square wave inverter when AC mains supply was on & events recorded as usual while switching between mains & square wave inverter power.

Event ID 61455: Battery backup transferred to AC utility power.

Event ID 174: Battery backup transferred to battery power due to a blackout.