What would cause gaps to appear in this LVP on the short side? It usually appears within 6 months at random.

Hello Shelly40601 and thanks for your question. There are a couple factors at play that may cause the Style Selections Rigid Core Luxury Vinyl Plank to cause gaps occur over time. 1.) the locking mechanism is not properly seated into place. 2.) The subfloor is not level and is causing deflection to occur, which cause the plank to bounce and come apart, or 3.) There was extra underlayment installed beneath the flooring that may be causing the floor to not be rigid, and have deflection. We would always recommend reviewing the Installation Guidelines (found in each carton or on the product page of the Lowe's website) prior to installing your new luxury vinyl plank flooring. Thanks again.