NEWBIE - Pool walls buckling while filling

Hello - newbie here asking my first question.

We have a 30ft round ABP. All posts are level to within 1/4", liner is next to perfect but one wall is buckling inward with only 8 inches of water. We filled only while in direct sun and shut the water off once the sun was off the pool. We measured and the water is within 1/2" depth all the way around the pool. We reconfirmed all posts are on the blocks and they remain both level and vertical. Do we continue to fill and assume that the water once it reaches the walls, will begin to push the wall out?

Completely nervous - I read similar questions on the forum but with no response and without being a member, I cannot view some posts. So I apologize for the duplicate question!