Not sure if this an actual bug or simply something I have not done yet/correctly.

I have played all of the VV games and tend to play them through to what seems to be the end point before visiting the forums.
I thought I had just about finished but came on here and saw posts about puzzle 17


when does this puzzle appear?
I have finished the 16 puzzles, converted all heathens, have built 3 huts, the love shack, nursery and clothing hut - completed the relics colection and have 1 remaining science object to collect and my population is 95 I have also


so the oly thing I can see left to do is collect the last science object - I do keep



Any help or suggestions would be gratefully received