This has been an issues for several major releases - and is present in the current release (16.1, build 1628)
Tested on Windows 10 and Windows 11
1. Create a new diagram element
2. Right-click and select "Properties"
3. Under Responsibilities, click "Files"
4. Set Path/URL to something ("
https://www.example.com")
5. Accept default Type: "Local File"
6. click "Save"
7. click Type, and select "Web Address"
8. Notice, the change does not enable "Save" - but if you change the URL or the text block (description?) - then "Save" is enabled.