Dimension Tool will not initiate if the object below the cursor is a Symbol

I am working on a document that needs to be dimensioned from one feature to many other features. As you can see in this screenshot, the cursor is indicating that I can not initiate a dimension element. The problem is that the object directly below the cursor is a Symbol that I created to indicate my center marks throughout the document. The only way I can get the dimension tool to work again is if I Unlink the Symbol or turn off the Layer containing my center marks. My question is why? What would be the reason for this functionality?