Latex paint can "reactivate" a bad adhesion of the mud to board. 

And the board surface paper may look good, but if the gypsum is crumbled or missing a bubble looking area will probably show up, again with the moisture of the paint softening the compound.

Butt joints really should be staggered on walls and ceilings.  More stress and movement on a continuous joint across several boards.

What I usually use is screws 8" on butt ends, 10"-12" in the center, mesh on all except the corners, 20 min sheetrock brand drymix, and if I am on the job a few days I'll use the green lid in the corners. I havent used paper tape on beveled joints or butt ends in years though I have fixed many, many, many bad tape joints (mostly from DIY homeowners) when paper tape was used. I found its usually poor bedding when the paper tape bubbles.

As for your mesh tape bubbling down on your butted end...... If there was a gap, and you filled the gap with compound then applied the tape, gravity would make the compound push the tape down as it would sag out of the gap. Check to see if there is mud or air (empty space) behind the bubble. Paper tape is easy to removed and replace. Mesh tape, not so much. Is easier to run your knife along the crack or bubble and reapply new mesh. They also make 6" tape. I use 6" tape when repairing a DIY'ers attempt to do drywall.

For your crack issue, Is it a straight crack or does it vary? There are many reasons for compound to crack. In this case, without seeing it, I would rule out movement and lean more toward heavy compound application (too thick of a coat will crack) or again a gap. But its tough to determine without looking... Feel free to post pics.

Good luck!

... Perfectionism may be the problem.  I was a perfectionist when I first started taping, and pressed too hard, trying to get totally smooth coats.  Which pressed out too much mud, allowing air in, creating bubbles on the next coat.  I have found the opposite problem from you:  If I don't have a gap between sheets, I more often get bubbling.  These days, I want about one -eighth gap and set paper tape in mayo consistency durabond.  The thinnish consistency makes it easier for me to load mud into the gap (which seems to hold better in the long term, sort of like keying plaster when using lath), and forces me to press more lightly when setting tape, aka I go a lot faster than I did when I was new to taping. 

The rules of taping: 

Mesh tape(self adhesive):  apply tape to seams, use SETTING type compound (Durabond is OK , but E-Z sand is better,IMHO, because it's sandable) apply 1st coat, let set , apply thin second coat , and touch up with final coat as needed.

Paper tape(non-self adhesive): apply bedding coat of JC, apply paper tape, smooth and clean joint, allow to set-up, apply second coat, let set, apply 3rd coar if needed, sanding in between if needed, but there shouldn't be to much sanding needed.

The trick is to apply the compound SPARINGLY, smooth with the knife and WAIT till it sets up, let the small ridge lines stay and sand them before the next coat, that is far quicker than trying to apply a "perfect" coat every time, apply, smooth, and let it be!

Your seam bubbled because the JC is water soluable, and when you primed with the latex you were just adding water to the joint, which caused it to swell, hence the bubble. Mesh is for SETTING type compounds only, for the 1st coat , after that you can use JC on succeding coats.

As to your crack on the butt seam, setting your sheets tight does not garauntee no cracking,in fact it may cause cracking over time. A small gap between sheets allows for some movement in the framing over time. Your seam most likely cracked because you used JC w/paper tape instead of setting type compound w/mesh tape, which is much stronger than JC, or maybe I should say your seam is more prone to cracking if you use JC on the base coat.

The TV shows never give the full scoop.

Hope this helps a little,

Good Luck,

Geoff