Hi There @tbingel
Thanks for writing in! Could you please try re-setting your .htaccess file by re-generating your permalink settings and see if that resolves your issue.
Head over to Settings -> Permalinks section, then select the options
Postname and save the changes to re-generate your permalink settings.
Also make sure that you're fully updated by cross referencing our version information here (https://theme.co/apex/forum/t/troubleshooting-version-compatibility/195).
If you're using a caching plugin, make sure to purge your server cache before testing your site again.
Let us know how it goes.