Related to my other post I have a problem with PageReferenceCollection losing its reference list.

As you can see I've made a custom property named PropertyMunicipalityListing which lists all the municipalities in Finland. User can attach zero or more municipalities to a page named AreaPage. This works fine. I can list all the municipalities attached to areas and display them to the end user.

But after a while municipalities gets lost. With debugger I can see that Municipalities property has gotten empty, its Count is zero (so it's not null). First I thought that someone has edited the page and done something wrong but page history shows that it isn't so. And top of all this happens randomly. Not every area page loses its municipalities.

Now if I go and edit area's municipality listing in edit mode, lo and behold, there they are, selected just nicely! So the custom property knows about them but PageReferenceCollection has lost them. Republishing the page repopulates the PageReferenceCollection.

How this can be?