Admin bar disappeared

All of a sudden, the top admin bar has disappeared from the front page when I’m logged in (it’s visible in the backend).

I’ve Googled this and tried all the solutions:

– Enabled the “Show Toolbar” in user settings
– Checked that there’s a get footer code in the footer.php
– Tried enabling debug mode, don’t see anything
– Disabled ALL plugins
– Switched to default WP themes

^ None of the above solutions bring the admin bar back, it’s never visible.

I have multiple WP sites, and I see the admin bar on all other ones except this one single one, so it’s not a browser issue (tried with different browsers, too).

Is there a way to fix this?