This is happening in Chrome and IE11.
If I have uploaded files (see below) and then come in and make ANY change to that page...

undefined

The files get wiped out ... ? (see below) undefined

(above I unchecked a checkbox and saved the page. Came back in and the uploaded files are wiped out.)

Finally all these pages are reporting an error with Leafleft.js... dont know if this is the problem or not? undefined