Users cannot access wp-admin dashboard to edit profile

I have several multisite setups, all using more-or-less the same setup and plugins/themes etc. However, on my latest setup, I created a test account, but can't access the admin dashboard to change my profile. I get the following error message:

You do not have sufficient permissions to access this page.

I've done extensive searches for this issue, I've disabled all plugins, made sure my database prefixes are all correct, cleared browser caches, tried different browsers, but nothing works.

I can access my network and site admin dashboard, it just appears to be the user dashboard that's inaccessible. So stumped!