It's no bug
I once had this issue in ksp 1.6
All you need to do is go into your game data folder where inside it says "squad" and "squad expansion" and you need to make sure the mods are along side it (doesnt matter what order) like this:
Squad
Squad expansion
KAS
(Same with any other mods)
And make sure there isnt any other folder called "game data" in your game data folder as the game gets confused with the files
It should work as it I have KAS now in ksp breaking ground
I hope this fixes it
Reply if it doesn't