Transmission not shifting properly?

I would start by checking the codes this guide can help:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

This guide can help as well:

https://www.2carpros.com/articles/automatic-transmission-problems

Make sure the transmission is full of fluid and if so with no codes I would replace the input shaft speed sensor which can cause the problem of the transmission not shifting. Check out the images (below). Please let us know what happens.