Attributes disapear/not imported (Alidropship)

Hello,
I encoutered with a strange behavior on my website during product import process. Variations miss imported attributes. But when using a plugin like wp all export, all attributes are in place for each variations. Then after an import (I use it to update variation images in bulk and other stuff for parent products), all the variations have their attributes like it should be since the begining.

Have you ever been confronted with this problem?
Do you have a solution to suggest?

I already tried to disable plugins and it didn’t work.