Here are some things I had trouble with incase someone else is trying to get variable rate jumps to work and stumbles here.
VariableRateJumps change the type of integrator.u to the type of ExtendedJumpArray, so you need to use integrator.u.u to get your matrices. Also it changes the type of the solution to ExtendedJumpArray so that your sol.u is now a vector of ExtendedJumpArrays. Hope this someone!
Also, saveat seems to be broken for VariableRateJumps.