Mob Do Not Drop Items And Points When Executed

I come through this ticked to report a problem that I have been experiencing even before the recent update.  I've been playing in a world created for a while now so that an online friend and I could come and explore, but at a certain point, I realized that animals, enemies and other interactions were no longer dropping items and experience points, whereas at the beginning everything was working as it should.  I ask that you can investigate and resolve this problem as soon as possible and I hope that I don't have to delete my current world since we have dedicated a lot of time to it.