I used a random seed after the update and jungle areas only came up at the corners and were small but from the few jungle trees I chopped very few saplings dropped after a short while. So the do drop. You just have to be patient. I have not come across any
pumpkin seeds in any abandoned mines as of now. I fined more pumpkins randomly about.
Handy tip: you can place 3 oak saplings and just one Jungle one in a square and then bonemeal yourself a huge jungle tree. Also, if you place them up against a wall with no room for the tree to grow and then bonemeal it, the oak saplings will turn into jungle
saplings. This is a handy way to build your jungle saplings for a tree farm.
If you are lucky you can see the saplings floating in the leave blocks. Bang them and ya got a sapling. I usually just cut the trees and walk around chopping others and return for the few that drop. It is easier where the jungle is the least dense......
They don't drop as often as others i found the best way was to just build the big 2x2 trees they drop more sapling and farm them that way as I didn't want to start destroying my jungle... but I would say for every 4 saplings I was using I was getting 6-10