Super fast blinking signal LED --> FOCBOX

Hi! Anyone had this issue? It happens when I pull or push the trigger. On both focboxes. I am pretty sure it should keep flashing instead of blinking…

But still the board works great - I can ride etc but when I am at very low speed, motors kind of weird brake (Only when signal led is blinking). When I lift a skateboard and pull the trigger, wheels are rolling OK but when I release trigger, sometimes they are slowed down by some force for a ~0,2 and they stop/move slower (also when led is blinking)

As I unplug and plug everything again, It works ok for some time but sooner or later it blinks fast again when I pull/push the trigger.

I am running split y ppm.

My setup: 10s 16ah 30C li po. (4x 5s 8ah 30C) 2x 192 kv turingy sensorless 2x focboxes mountainboard 1:4,55 reduction

And: https://hobbyking.com/en_us/quanum-2-4ghz-3ch-pistol-grip-tx-rx-system.html

Do you have any ideas how could I solve this problem?