ilmars:
I just used the current version of the Mission Editor (2.24.5) with my "PeabodySimple" mission as you have done. But my results are different.
In my case, the .wav sound files DO play correctly in the mission editor, and I'm able to generate corresponding .res files by compiling the same mission source code that has always worked correctly with the older version of Aces High (2.12.4 ME and sim).
HOWEVER, the mission won't "fly". The Aces High flight simulator front end plays the first .wav sound file correctly, but then it always crashes immediately upon termination of that first .wav sound file. The simulator locks up completely with the infamous "White Screen of Death", until Windows halts it with the usual "has encountered a problem" dialog.
If I delete all references to the .wav files from the mission source code, then the mission compiles and flies correctly (but of course there are no audio briefings or other mission-specific sounds).
This same symptom has been reported and confirmed by others in the "Aces High bugs" forum.
I'm going back to v2.12.4....