I have also opened a ticket for this, but I have been plagued with this bug for ages and I'm wondering if anyone else has had anything similar! Let me explain the scenario:
I create a song which includes the virtual Instrument Superior Drummer. I then open the project Page and import the file in to there.. I then imports all of the song data. Whilst importing, I can hear there are no drum sounds from Superior Drummer. If I let it finish, then right click on the song in the Project Page and select 'Edit Song', the song then loads and I am now in the song page. If I just do anything at all to force a save (like mute then unmute a track). I then save the song. I then click on 'Project' at the top right of the song page and it takes me back to the project. I then click on the red wrench, and I can hear the drums are now importing. I then save the project and if I do a digital release of the track, it sounds fine with all the drums. This only happens with Superior Drummer. Any other virtual instruments can be heard straight away.
If I then open and edit this song the next day and save it, next time I open the Project Page it knows the song has been updated, but if I click on the red wrench I can hear straight away the drums are not heard again. If I simply cancel the update, then right click on the song and do the same simple edit again to force a save (mute, unmute, move a slider then back again etc), after returning to the project page and clicking on the red wrench again, the drums are heard. This happens every single time with any song that uses Superior Drummer. If I bounce the SD track (or tracks if they are exploded) to audio, this issue does not occur. This happened with V4 and is now still there with V5. Someone needs to run through this procedure as I can re-produce it easily.
My hardware is Presonus Quantum.
Windows 10 Pro (Dell) PC with dual 18 core (36 total) Xeon CPUs with 128 gig of RAM. It is not a resource issue!