When the user tried, they got an error. I was able to recreate it:
In my original test, I was using a non-sandbox cube. When getting the error, I had switched to a Sandbox enabled cube. it was not making sense to me, then I remembered to look at the dimensions. Here is what I saw:
You will notice in addition to the Sandbox dimension another dimension was added "CellProperties". This is not an attribute dimension but a real "Hidden" dimension in that it acts like an attribute and does not appear as part of a standard retrieval. This dimension is only added when Sandboxing is enabled. Looking at the member I saw there were three children:
When I added the member EssValue to my sheet LROs could be added. So what is this dimension and what is used for? I put all three members on my retrieval sheet and did a refresh.
EssValue returned the data value that is part of a normal retrieval. This means to be that "CellProperties" must default to this value. EssStatus gave me a the number 1. Hmm what does that mean? If I cleared out the member both the EssStatus and EssID went to #Missing. Entering a number and I got :
It changed to a 2. I remember in the beta talking about this. If I remember correctly, 1 means it was loaded from a dataload. 2 means user input (Submit). I believe a 3 means it is the result of a calculation.
The EssID, is really meant for relationships in sandboxing and approvals and really has no value to an enduser.
So you get two tips in this post.
1. How to get LROs to work in a Sandbox enabled cube
2. What that mysterious hidden dimension is and what it is used for.
OK, now I can digress