Limit Throttle to not working

[costa-astro]

Mechjeb 2 Throttle control stopped working, this issue appeared by itself a few months ago.
Somehow the "Limit Q to" and "Limit Throttle to" features are 'linked' too: when I modify one the other gets the same value (for instance if i put "40" in Limit Throttle To, Limit Q gets instantly set to this value), but Limit Q to feature still works.
I couldn't find anything in KSP's LOG files about a possible MechJeb2 error.
I still don't understand whats happening here. I reinstalled the mod several times from the official GitHub link, from CKAN, even the game itself, even steam, I tried to purge the steam cloud (in case there could be any corrupted file...), nothing worked. Even on blank vanilla KSP !
Could it be a bug from my PC ?
Does somebody has any idea of how this could be fixed, somehow ?

PS: I posted the same issue on reddit a few months ago, so I'm trying to reach for help here.