Hi There @yoggelino
Could you please try re-generating your .htaccess file by head over to Settings -> Permalinks section, then select the option postname
, save the changes and test your issue again.
Please make sure to clear all caches when testing your issue (https://www.wpbeginner.com/beginners-guide/how-to-clear-your-cache-in-wordpress/).
If you have an active child theme, try disabling your child theme temporally and see if that is related your child theme customizations.
If you’re still having this issue, then you need to disable your 3rd party plugins except Cornerstone plugin and then test your issue further. If the issue resolved, then you can activate your plugins one bye one to see which plugin causing the issue.
If you’re still having issues, please provide us with your WordPress login credentials in a secure note to check your issue further.
Thanks!