Hi @gledys
It is a bit hard to answer why you are experiencing this issue
The best advice I can give is the standard fault finding and fixes.
I first advise you to clear the cache and cookies. You can also try to reset your permalinks and try again.
The issue could also be due to a theme or plugin conflict
Themes:
As a test, switch to a default theme such as twenty-twenty and see if this fixes it.
Plugins:
If that doesn’t work, also deactivate all plugins apart from QSM and see if this fixes. if it does, re-enable one at a time to see which is causing the error.
If you cannot do this to your site (say because it is live) then use the ‘troubleshooting’ features of this plugin to let you test without affecting other users
https://en-gb.wordpress.org/plugins/health-check/
Regards,
Sumit
