My app stopped working - Lookup fields

My app stopped working - Lookup fields

I've tried 3 browsers, MS Edge, Chrome and Chrome on a Chromebook.  And my App stopped working over night.

I have two lookup fields,  The first lookup field never sets up the second lookup field.  It was working fine yesterday and today its not working.  I've not touched my code or changed anything as its a production program, so I'm at a loss as how to fix it.

Thanks
Andy