This is actually kind of common with Otis drives in my experience. Mostly with OVF30 and 40 though. They seem to start getting low lin, buss undervolt and PLL unlock faults. I had gone around with the building about incoming power etc. and finally sent the drive to ITS and it’s fixed. It may be an elevator issue. If you really suspect building power you need to hook up a 3 phase voltage monitor, your shop should have one.