Quoted from Hwawonyu:
Bet they do but just cant show them or discuss.
Let's say for the sake of argument that JJP was shown an early (but probably mostly edited) version of the 3rd film 6 months ago, and that they started to incorporate art and sound assets from the 3rd film into a prototype late summer.
I don't see how JJP could pull this off without having multiple physical prototypes, unless they were never planning on doing any demos and we can see that wasn't in the cards because they have done two demos so far with another coming later this month.
That would mean that the prototype that people are seeing now is probably a very old prototype, at least one major revision behind.