After hours of trying a number of things, I found a work-around that got me to the Health Declaration (and thus the App Content).

In the documentation for the Health Declaration form there was a link but the link took me to a sign on and the sign on brought me to the dash board and still no App Content.

I found that my default Google account was A but my Dashboard for the Play Console was in Google account B. If I made B my default Google account and I clicked the link in the Google Help Google Help Center: Health apps Declaration , I still needed to log in but now when it logged in, it took me to the App Content and thus the Health Declaration. Who'd of thunk.

With this work-around I still cannot get to the App Content from the Dashboard. If someone knows how or why I cannot, answering this might help others.

But for now I have a work-around.