u/Dizzy-Peanut-1040

Hello, I drive a AWD 2016 Infiniti q50 VR with the 7 speed transmission (RE7RO1H) and I’m so confused on whether I have valve body issues or a different component is bad. About a year ago, I took my car to a shop for a drain and fill, plus changing the gasket. The shop never put on the new drain plug washer, and my transmission ran low on fluid for a week because I didn’t catch the issue. Ever since then, it violently shifts into 3rd after I let it sit for 10 mins after getting up to operating temp. Ive had the trans, and valve body checked by the dealer, and they found nothing besides low fluid. It seems the violent shifting forces fluid somewhere internally (transmission is bone dry externally), as I only experience low fluid related issues after the violent shifting. I am lost on what the real issue could be. The car is going to a trans shop soon for the issue I mentioned above, but before then I wanted to share this here in hopes someone understands what I don’t.