Motors twitching when armed. PWM increase when armed

What can be pushing my 2 motor servo outputs up to 1010 when armed (manual mode)? The throttle input channel is around 980 and when disarmed they are 1000. I thought it may be rudder differential but I have just disabled it and still the same. Using DShot 600 but I guess the shown PWM shouldn’t really change when armed?
There was no twitching before I put a CRSF RX in and there is no twitch on NON DSHOT modes.

I could probably set MANUAL_RCMASK to pass the throttle setting straight through but Im still curious why the throttle output jumps up then armed.

On second thoughts this may not work. The motors are on 1&2 and the throttle is on 3.

More tests this morning. I have tried changing ESC settings, lowering and raising the minimum PWM but no change. Have turned off ESC auto calibration. No change.

If there is a setting that causes the motor output to slightly increase when armed then please advise. The other problem is that the motor break never operates as it does not register as fully idle.