Heya, just to close the topic on my end. It turned out that inverter input mosfets were shorted and respective controller was fried (due to drain to gate short on the mosfet).
I replaced both mosfets (Q6 and Q7) with CSD19506KCS.
The new ones are much oversized, but thanks to much lower Rds(on) than the originals heat up less also.
Controller was replaced with the same UCC27424QDRQ1.