Microsoft’s office URI schemes conflict with the list separator of allowed_href_schemes.
https://docs.microsoft.com/en-us/office/client-developer/office-uri-schemes
I can’t allow scheme like ms-excel:ofv|u|https for the full link ms-excel:ofv|u|https://contoso/Q4/budget.xls
Having an escape character or quoting the scheme string would be great.
This is not a web compatible scheme, it refers to different concepts.
I checked out the code and it turns out that the separator is chosen intentionally because all the schemes are stuffed in a regex and the regex is used to match links.
In the settings I used ms-excel:.+ to bypass the filter and now my links work as expected.
Turns out it’s not a bug, it’s a feature! 