I have the same problem, but a little bit different!
I can do a simulation without problems, in MANUAL, STABILIZE, AUTO, with waypoints and so on... but.. not always.
I mean.. in the morning, for example, everything works perfect. After lunch, (when I switch off my pc and then turn on) nothing works and I have the same message: "NO SIM DATA" in ArdupilotSim.
It's funny, I know, but for me it's a problem because every setting is ok in X plane and I don't know where can be the problem.
(In APM the waypoints remain in EEPROM...)
Thank you in advance for your help!
The same identical problem. But I cannot find a solution, because sometimes works perfect (and there are no problems) and sometimes not.
Let's hope to find a "revelation" :)