I run SITL fairly regularly and as of a week ago the plane code fails to launch. The same is true for multirotor and helicopter, but not rover.
The error: “The code execution cannot proceed because cyggcc_s-seh-1.dll was not found. Reinstalling the program may fix this problem.”
Reinstalling / updating did not fix this problem. Hopefully someone else has experienced this, I have not found any mentions of it pertaining to MP.