Hi,
Have you tried with Tomcat 9.0.21? I always had issue with Tomcat 7 and 8 series. On your current installation, have you tried to stop the server, restart the PC and start the server?
Hope one of these steps will help you in resolving your issue.
Welcome to the ODK forum, @Thomas_E! We're glad you're here. When you get a chance, please Introduce yourself here!. I'd also encourage you to add a real picture as your avatar because it helps build community!
Thanks,
Imran