Thank you for reporting the issue. It could be a rig issue. Can you upload your custom model for us to inspect ? If it's private you can send the model to email@example.com together with the problem description for our support team to inspect.
Kirk Ruebenson See the attached test result of your video generated by https://portal.deepmotion.com/. It worked ok for all default characters and none of the characters sunk into the ground. Are you sure you are not using custom character ( New Animation -> Custom) ? The model in your video recording does look different from our default characters.
Sorry, I really don't remember using a custom character, but I guess I did. The pivot was probably in the middle. Anyway, thank you so much for your service, I hope to use it more in the future. Good luck to you! Thanks again, Kirk.