Hello feathered29,
Thank you for sharing your problem.
Because of the OS update, system extensions may have some issues. You can try to run the DisplayLink Support Tool, which you can find
here.
It might be helpful to plug the dock into a different USB-C port on your Mac and see if it behaves differently.
What you could also try to consider is contacting Dell directly for assistance or Apple (since the issue appears to have occurred as a result of an OS update)