Last year, I bought two Maxxis High Roller 2,35" UST tires for my Mojo HD, running them in the rear teamed up with Maxxis Minion DHF 2,35" in the front. The first one started forming bubbles after couple hundred kilometers. I thought it was one bad piece, so I threw it out and replaced it with the second tire.
This is how the second tire looks after half season of riding. Rubber layer started to separate from the wiring and at least 10 bubbles formed on the surface, some of them joining together.
On the other hand, filled with No Tubes tire sealant, the rear wheel held pressure and was ridable until the center tore apart. Even after this I was still able to get home safe.
This same thing happened with my High Rollers. I think its an issue that their UST tires have across the board. When you add sealant (Stan’s at least) the fluid migrates between the casing and rubber forming bubbles.
The problem isn’t so bad if you keep and eye on the bubbles and then just prick them with a pin. Stops the spreed of the bubble (and the rubber to casing seperation) and keeps the bubbles from bursting when the rubber is torn off the casing.
Not ideal but i can live with it considering i will pretty much only run high rollers on my rear wheel.