If you right click on the contentArea's items (the blocks and/or pages you've dragged in) and look at the div with class="dojoDndItem epi-overlay-block". Do they all have different id's?
Hmm, ok. What I'm searching for is a problem I had myself a while back. What was my problem then was that I had not added "data-epi-block-id" on the the div tag that was out the container for each page/block. The method I used then was that I overrided the ContentArea display template and added this value myself by specyfing an id.
I'm far from sure this is your problem but I think you should see something like this if you look on the div tags that surround each page/block in the content area in admin mode.
id="uniqName_94_2" widgetid="uniqName_94_2"
I used chrome and took inspect element to see this. But as I sad, I'm fair from sure this is you problem. Just a guess.
I have a page with block properties. These blocs contain ContentArea properties, which we use to define collections of page links. ContentAreas seem more convenient than the usual LinkItemCollection because editors can use drag-and-drop.
However: Now it seems the contentareas are loosing their values for no apparent reason? What could cause this?
The site is EpiServer 7.1 MVC.