Watched my buddy fight a paper tape corner for two hours last week. The paper kept bubbling no matter how much mud he used. He switched to mesh and the thing went smooth in twenty minutes.
Last time I tried paper tape, I must have used a whole bucket of mud and still got more bubbles than a kid's birthday party. Ended up with a wall that looked like the surface of the moon. My partner still laughs about it every time we pass that room. Swore off DIY drywall after that, but maybe mesh tape is the secret I was too stubborn to try.
Tbh, did he try wetting the paper tape first? My friend had the same issue until he started damping it a little. Said it stopped the bubbles right away.
What if wetting the tape just adds another thing that can go wrong? I've seen it make the paper too weak and it tears easy (which kinda defeats the purpose). Maybe the real trick is using less mud from the start.