What’s in this release over Preform 1.8?
I do know what’s missing in Preform 1.8.13.
If you scroll through each layer to make sure that all parts are supported. After reaching a layer which isn’t supported, you edit the supports and add one to the spot which needs supporting. However, in the new Preform, when accepting the changes, it doesn’t go back to the layer you were on. You have to scroll back to the layer and continue. The last version remembered where you were after editing. Apart from that I haven’t noticed any differences compared to 1.8.
Hopefully someone from Formlabs can enlighten us 
minor bug fixes is all