I have seen 'bubbles' under bases for a number of reasons... as mentioned already too hi a temp when waxing or repairing can detach the base and leave a bubble...or waxing a cold ski - like in a garage too fast.......once a lady brought in her volants and there was a bubble right under the foot of the ski and the consensus was this was a manufacturing defect because she never abused her skis, the base maybe was never bonded properly.......another thing can be core damage under the base that eventually causes a spot de-lamination of the base..........or edge and water getting in / freezing / expanding ........
Armadas are usually well made and the AR6 has a park base so u got an interesting one here....how it happened isn't as important as does it affect performance and how to fix it....some of the guys thought of cutting out the ptex bubble in the volants and then seeing what was underneath and epoxying it back in or epoxy the bubble with a heedle.......but it was too much labour and and trouble for the shop to do it without knowing if they could even fix it...so the boss said move on..