Hello, the pulse function was meant to trigger pulses 100ms or longer.
The issue here might be that the task scheduler is running in 10ms intervals and it can have issues if you call function with 10ms or less from time to time. My guess is that with 20ms it might work, but really this pulse function or relays at general are not suitable for this short pulses. I would suggest to set 50ms pulse to be on safe side.