I cannot figure out why, when I use section access to limit the data a user sees for a particular field, that it works perfectly fine for the users MIKE and JOHN (Admin's) when accessed via local opening of file on desktop, but when accessed via Webview it will not let me login as MIKE or JOHN (Admins), but all other USERS (Bob & Ally) work. Please help!
You should set "TESTFIELD" field to value "*" (all field values, listed in Section Access) or some other value (if those admins should work with some particular values). The best practice is to fill ALL fields with some values in your Section Access. In other way it will work incorrect in some cases.
All users accessing the document in the access point will get USER as ACCESS level, not ADMIN access. That means that the special blank value won't work in the ajax client to let admins see all values. See this discussion for a solution: Section Access - View all data