Cannot Authenticate or update site Tracking Code

Hello,

I am attempting to authenticate analytics in the settings and update the tracking code, but any time I try I am given a "page not found" error and the site appears to be attempting to open the settings page on the front end rather than the backend. Any ideas what could be the issue? Thanks in advance for any help!

Additional: I just tried to grant access for support but the same issue is happening when I try to open the WPMU dashboard..

*Edit: Support Access has been enabled