PROBLEM with Menu

Problem with Menu built by WordPress

Site created, everything works amazingly well – and then the site was moved / transfered to a main domain.

Now the site is perfect, except for the MENU.

For a front-end/visitor – the menu is fine, except for the last button. They can see & click on the menu – no problems.

The problem is in the back-end / WP-Admin. Every time I try to add a new button/page to the menu – it saves, but reverts to a custom link / not a true page – and then the other items on the menu move by itself to the next spot over on the top row. Meaning items on that row dissapear, and nothing has been added as a sub-menu.

Is this something to do with the database and moving the site? I appears there may be a internal problem – however I really URGENTLY need to find a solution to this.

Please help and reply. Thank you.