drywall tape coming off
I wouldn't advise mesh tape in an angle.....using a setting type compound might help from having a recurrence of the problem. Moisture is only one possibility of why the tape came loose to begin with. Movement in the framing, too big of a space between the wall/ceiling boards, not enough mud under the tape (as "crawdoogie" mentioned), just to name a few. Keep the area to be re-textured as small as possible (just the width of the tape if possible) by using a small knife to retape. Mud over the tape and texture. If you're just doing an area an inch or two wide, a spray can may just be "the ticket". Paint to match existing.
If you can read this, thank a teacher. If you can read this in English, thank a soldier. Support our troops.