I framed my shop building using 2×6 studs, 16″ oc. Fiber batt insulation. I hung and taped the drywall. I used screws and foam-type adheasive. Used paper tape and Durabond 90 setting compound to bed the tape. I hired an experienced drywall guy to come in and do the finishing coats (2 coats of Plus 3) and sanding. After about 12 to 18 months, I started getting cracks at some of the seams. The cracks are just to the right or left of the edge of the tape. There are no cracks in the paper tape.
What did I do wrong, and what is the best way to do the repair? I know that just putting more mud over it is not the thing to do.