Assuming you are indeed on v0.7b, please standby... allow me time to open the project and review your specific issue for analysis and a recommendation...
Edit:
drisarter You are indeed on v0.7b. The issue you are having is the export code conditional seeking how many open (non used) export save slots are available:
Python:
...
if gamePass == 1 and not mp1_2.gamePass >= 2: # Sancho: see post note below for more info
...
What I'm having difficulty thinking of is why in the world on Mac would the MultiPersistent data file creation would result in a "nonetype" error... it's as if you have write protections in place and the initial MultiPersistent file cannot be created and therefore the open slots not existing at all.
Post Note: For clarity on what the conditional is doing (see my "Sancho" note in the above code snippet): this initial portion of the conditional is seeking if the first save slot is used or not and if it is used to go to the next part of the conditional, and if it is open (unused) then proceed with the commands under this portion of the conditional.
Are you running the VN directly on the Mac or via a VM (virtual machine)?