My platform ad spend didn't increase today, but orders dropped. Should I check the Buy Box or inventory first?

I checked the marketplace report today; ad spend was normal and clicks hadn't dropped, but orders suddenly fell off a cliff. My operations colleague wanted to increase the budget first, but I decided to check Buy Box share, sellable inventory, shipping lead times, and pricing rules. It turned out an automated repricing rule had pushed the price below MAP, causing the platform to pause some…