Assist uncommanded jerky movement with turbine spool up. Interference?

I have a Su27 with twin turbines and cb200+ assist6.

When spooling up the engines the tailerons start making unwanted fast jerks/twiches.

I thought the problem was with my setup, but now today I had similar twitching in my Eurosport ! Assist12 with satellite. Ground running engine I am able to get unwanted elevon deflections without control input when spooling engine up from idle.

I saw the plane making jerky movements in the air too.

Twin was jets munt vt80 setup and ES is JM 200 XBL.

I have no trust to this system!