if you still struggle with this 8 months later: I had the same problem. I figured that there are pieces that fit perfectly on both sides. The edges are basically flipped. So lets say a piece somewhere on the top left of your half fits in the shape but not color, you need to put that on the bottom right. I did this with my friend group and it took us 9 hours to get the edge done, bunch of flashlights, trying, looking, moving etc. it was a random coincidence when I realiezed the whole thing was flipped. Once I fiugred that out, I knew I could easily work to fiugre it out

Edges are 80 X 100 pieces.

El puzzle ya no lo tengo, lo vendí

El puzzle ya lo vendí, es marca Educa

Thank you, luckily i also found and got this puzzle now.

Yes, the puzzle comes in two bags, 4000 pieces each.