Files saved in MB3 Don't Work (Re-Solved)

[Boydbob]

I can load an existing MB2.5 file into MB3 or I can create a new MB3 Session and import an audio file into it.
When I play the Session file, everything works and looks as expected. I then "Save" or "Save as" the file and exit MB3.
When I load the file I just saved:
I get no audio going to the Master Out and there is no "master out" selection for the tracks, although I can select the Sound Card direct outs, which do work.
Also the Mixbusses no longer show up above the tracks in the Mixer window, even though they are checked.
I have two interfaces - An RME Babyface - and a Focusrite Scarlet Solo. It doesn't matter which one I use, the result is the same.

Re-Edit - The problem was still happening, and - "Doh" - I suddenly realized I also had Ardour 4 installed, and when I clicked on the Session name to load the project, it was defaulting to Ardour 4 instead of MixBus 3.
Starting MB3 first and then loading the project was working as expected. So I deleted Ardour and set MB3 as the default for session files.

[Jouvert]

Did you install using administrator rights the second time, as opposed to the first ( like in Windows 7) ?

Jouvert