7.8.2 Pro - stuck on login when accessing BWC modules

7.8.2 pro in the past couple of days I've not been able to access BWC modules in my TST server. Including Campaigns and Administration.

I can log in fine, navigate sidecar modules and use them just fine, but when I go to Campaigns, for example, it bumps me back to the login screen with the following URL and I'm unable to access that module. The same happens if I try to go to the Administration module.


The only change I know of is a test by our sysadmins to switch from APC to Zend OPCache.  

What would cause this authentication issue?