After publishing to service, all of the decomposition trees in our reports are defaulting to show the first dimension in the fields list (North America in the screenshot) - even though when we publish them there is no selection made. As of last week, all of the decomp trees we use would show only the measure by default as the starting point.
There also is not an X for us to deselect this default until an additional dimension is added.
It's a known issue , the ID is 309813755 . The product group is working on the fix for this issue, but it still needs some time before it is available in the product environment. Please be patient for the fix. Thanks for the understanding!