Same problem here
(just create my new account because i want to solve this)
KSP.log here
(tried Zero MiniAVC and ran it before, the problem still exist)
(I agree with @rextable , he said it was a mechjeb2 problem because i recently updated it, and the problem occurs)
--- EDIT: ---
I scroll back the ClickThroughBlocker version to 0.1.9.3 and MechJeb v2.11.0.0, everything works fine now. You should investigate why
this problem occurs.
P.S. I tried delete MechJeb2 mod and runs the game with newest version of ClickThroughBlocker, and it works perfect too.
Hope this helps,
Eric