Hello,
Please make the full backup of your site as well as the Theme settings export and check the issue on the Storefront theme to detect if our theme causes the problem.
If you see the same on the Storefront, deactivate all the plugins not related to the theme, switch the parent theme, and check the issue, If the problem has gone, activate the plugins one by one, checking the issue to detect which one causes the problem.
Regarding file .htaccess our theme does not influence this functionality. Check your Permalink in the Dashboard > Settings > Permalinks, if you configured custom URLs, set the default ones and check.
Best Regards
.
