When finishing the tutorial, I noticed that the MetaSound audio (SFX_Jetpack) does not support restarting the jetpack after stopping in mid-air. Starting the jetpack the first time plays the start and loop WAVs correctly (JetpackStart and JetpackLoop respectively), but those WAVs will not play again until after the JetpackEnd WAV finishes playing (all three of these WAVs are configured inside SFX_Jetpack).
To fix this I duplicated SFX_Jetpack to create SFX_JetpackEnd. No changes to SFX_Jetpack, but in SFX_JetpackEnd I pointed the “On Play” input to the JetpackEnd WAV instead of JetpackStart. In BP_Stackbot I duplicated the JetpackSFX component to create JetpackEndSFX and pointed it at SFX_JetpackEnd. Then in the Toggle Jetpack function I did this which seems to support starting/stopping/starting the jetpack in mid-air:
