Can't delete OUGC announement bar

[DerMauch]

While trying to delete an announcement from the plugin, there was a short message (1 line, no mybb template) and then it immediately redirected to the "manage bars" page. The bar disappeared from the list, but is still visible from anywhere on our site.

We have rebuilt pretty much every cache we could find. I couldn't find any remaining bars in the MySQL database (prefix_ougc_annbars) either. Also, we are using PHP 5.6. Can someone help us?

PS: I've removed <!--OUGC_ANNBARS--> from the templates until I find a solution.