Re-saving permalinks solves the issue.

• Go to : Settings > Permalink
• Select your preferred format
• Click ‘Save’

• In case, you have already set preferred permalink structure, and getting 404 error, set something else, and save.
• Then, re-select the original one ( your preferred one). This will re-write the .htaccess file

If still no luck you may need to update your .htaccess file manually.
This is a server side issue and outside the scope of theme and theme support. Still drop a mail to theme support, we will have a look once.
Further it may need to contact to hosting service provider.