In case it is useful since I had similar problems in the past, I will tell you how we have solved it.
1- Never install the "deprecated server behaviors". Directly install the webasist extensions.
2- Uninstalling dreamweaver and reinstalling it did not help us.
3- Instead what worked was either to create another user account within windows (in case of being a mac I don't know what the solution would be) or to delete all the data from the C:\Users\"YOUR USERNAME"\AppData\Roaming\Adobe\Dreamweaver 2021
This causes dreamweaver to boot as if it were installed again (as new install). You will have to install the extensions after this step and all the sites will be gone. It's the closest thing to a clean install I've come across.