Stereo Busses Suddenly Go Mono When Project Opens

So I opened a project yesterday and all three active busses were in mono.  They weren't when the project was saved on Saturday and I was unable to find the source of the problem.  Some quick background:
 
Saturday:  One bus had 7 tracks routed to it, each track is mono and panned in various places around the sound stage.  This bus had one FX -- the Abbey Road Mono-->Stereo Reverb (it was playing in stereo earlier).  Second bus had EZKeys routed to it, playing in stereo (no FX).   Third bus was the Master, with no FX.
 
Sunday:  The Master played only in mono, even with the mono/stereo button showing stereo.  The EZKeys bus played in mono, also regardless, even though the EZKeys track showed stereo (and played stereo when I bypassed the Master bus and went directly to the output of my Focusrite A/D unit).  The 7-track bus was also mono BUT even the 7 tracks themselves played in mono despite pan selections.
 
I tried everything I could think of (clicking the mono/stereo buttons on/off, removed the FX in the EZKeys bus, etc.), but in each nothing changes.  Only when I bypassed the busses and went directly to the Main Focusrite output did stereo return.
 
I ultimately deleted the two non-Master busses, added replacements and everything worked fine.
 
Any ideas?  Thanks,
 
Steve