Motors only reacts to 50% throttle

I have weird issues (and I crashed copter once because of that) with BLHeli Escs.
Without any props in stabilise mode motors stop increasing speed after 50% of throttle (both oneshot and oneshot125).
Another issue is Escs initialization they start randomly and I have to arm copter many times to make all motors spinning. After that all motors spins on every arm till power disconnect. Lowering min thr to 990 doesn’t help.

Esc calibrated correctly, motor range and throttle range set to 1000-2000.

Any idea what else to check?

Hi Piotr,

Have you done ESC calibration with OneShot enabled?

Can you tell what parameters you have set? If you have a log (with LOG_DISARMED enabled) it might help.