The * next to a track name means that the track is frozen.
If the frozen track had no midi data on it at the time of freezing then, when it's regenerated, there will still be no data on it - thus it won't play.
Next time that happens, right-click on "Master", select "Unfreeze all tracks" and now regenerate. This might help.
Am I missing something when I want to move from RealTacks back to pure midi?
This will depend on how you moved from RTs to midi.
If you simply loaded an all-midi style to replace the Realstyle, then everything should work fine.
If, on the other hand, you tried to go to a midi style by removing the RTs from each individual track, the results will most likely be unsatisfactory. This is because not all Realstyles have an underlying midi style.
Hope this helps,