Unable to save concert in MainStage 4.3

In Mainstage 4.3, when trying to save a concert, I receive this error

"The document [my concert] could not be saved". Try using File > Concert > Consolidate to re-collect all Sampler Instruments into the concert".

Is anyone else having this issue? Or is there a fix coming soon? I'm sort of dead in the water on this one. I'm a long-time user (13+ years), and this is the first time I didn't wait before updating. Ugh.