Stream 5000 UPS?

So, I've got my new Stream 5000 and it's great device for backup - small, big capacity, good enough power as backup, and silent.
But the UPS seems to be not as advertised.

My setup is: main input, ATS for critical devices (refrigerator, AC, lights, some important outlets...) and everything is loaded for main line when it's live, and switches via ATS to a backup power (Delta series power stations or Stream 5000 now) when the main line is off.

It worked quite well from Delta 2, but the switch from Stream 5000 is definitely not as advertised 0ms (UPS mode is turned on in settings), it's more like 100ms, the lights definitely blink and AC turns off.

Is this something we can expect as a fix with new firmware updates?