Transferring world from 1.12.2 to 1.13 isn't working

Trying to load world from 1.12.2 in 1.13 results generating new world with the same seed but from scratch, without any buildings I've made before. Optimizing world from single player tab isn't working too. World download: https://drive.google.com/open?id=147m1Quq7iXTYcvKZHkOpITNu17nf5CX2