Step 1: Dowload and activate the All-in-One WP Migration plugin if you do not already have this on the WP install you wish to migrate.
Step 2: Export the site in question via: wp-admin dashboard > All-in-One WP Migration > Export > Export To > File and then click the green Download prompt.
Step 3: Dowload and activate the All-in-One WP Migration plugin if you do not already have this in the WP install you wish to migrate the site to.
Step 4: Import the site in question via: wp-admin dashboard > All-in-One WP Migration > Import > Import From > File and then locate the file you previously downloaded from the export.
Step 5: Save permalinks via: wp-admin dashboard > Settings > Permalinks, select the permalink structure you require and click “Save Changes”.
Repeat Step 5 (so you should have saved permalinks twice).
Step 6: Sign shortcodes via: wp-admin dashboard > Oxygen > Settings > Security > Sign All Shortcodes and then make sure you check “I have made a complete backup of my site.”, check all post types, and then click “Start shortcodes signing process”.
Step 7: Clear Oxygen cache via: wp-admin dashboard > Oxygen > Settings > CSS Cache > Regenerate CSS Cache
Step 8: Clear cache from any other caching plugin and/or from your hosting provider.
Provided you followed those steps in that order, you should be good to go!