I have this same exact issue, using VESC Tool. No idea why. I have been using sensored FOC on 12S because I couldn’t figure out why the BLDC motor detection didn’t work.
Only had a problem when moving to FOCBOX’s, with my TB vescs, bldc sensored worked fine.
The only annoying thing about FOC is the stupid hard braking at slow speeds <1mph
The sensor detection fails when the motor spins in the wrong direction. At least that’s what happened to me, in BLDC only, FOC was working fine.
I just had to swtich 2 phase wires and it went fine.
I’ve had this exact issue. Since upgrading the firmware on my FOCBOXs with the ackmaniac tool - they both detected in BLDC in the VESC tool but then one of the 2 wouldn’t in the new tool. I never managed to find out why unfortuntely however I’ve been running them in FOC (unsensored 168kv SK3s) on 12s for a few months now and had no issues at all. Much smoother start up too.