I personally think its a past job that someone did not layer enough mud over the crack in cycles that has allowed the tape to only be the outer skin.
What I would do is to pull off all the tape that is buckling and even into the areas that are OK, then use the mesh tape. I would apply some good mud to the area first, then embede the mesh into it and then trowel it out. Wait for 24 hours, trowel out again with a wider blade, wait 24 hours, then inspect it, sand it then apply another coat. I think that the different coats were not utilized then.