No dog in this race, but an observation from past experience... TL;DR
I think there may be a problem with the DTS digital printing and the proces of adding clear on top of it. When I worked at Grimes Aerospace, we were using an aerospace developed, hi temp silicone clear base infused with transparent colorants, which were either specfic pigmented material being locked into the matrix, or, if it was a chromatic dye, one that changed the spectral absorbtion of the actual clear base, but either way, they disrupted the adhesion process to the substrate material. If faced with trying to figure this out, I would say they need to look at the bonding strength of the artwork layer, the bonding strength of clear coat to the artwork layer, and the change in density across the layers. When the clear is bonded over the artwork layer, this “system” now has to rely on the bond strength of the pigmented artwork layer to the wood substrate for ALL of it’s mechanical bonding properties. Now at first, the clear is flexible, not fully cured, meaning all the chemicals in the clear coat preventing complete cross-linking of the long chained molecules has not vaporized yet. The physical force of the posts sharp edges provides the proper “preload” and as the clear finally cures to a hardened state, there are forces in the mix that intensify the strain on the wood/artwork bond, and when it fails, the resulting delamination spreads from the point of the force causing the clear coat deformation. Anyone serious about solving this issue needs to look at this as a system, not as individual processes that may or may not have a big contributing factor to the phenomena. This would require at least 4 to 5 months of R&D to totally understand all the variables and how to control them, and I don’t see a pinball manufacturer spending that kind of time and money to figure this out, unless your entire company reputation rested on it... the scientific method works, but it ain’t cheap.