How to create files .uexp .ubulk?

Hi guys, in my old project I had these files once cooked the game test.uasset test.uexp and test2.uasset test2.ubulk, was a project where I used the UE4 4.15.1. A few months passed and I updated the version to 4.15.3, but this time when they cook the game I find only files .uasset, what changed???
I checked the options and it seems all the same, in the end my project works the same but I’m curious about what I’ve changed without realizing it, and I want to understand how they can create these files.
Thx.

It could be because I have removed MV Studio???

No one who can answer me?

Bump wouldn’t mind answer to this did you ever figure it out? I need ubulk file