The drop down box for configured component replacement in an assembly has disappeared

When I click on a component in an assembly that has multiple configurations either in the Model Tree or on the model itself I used to get a drop down type box that would let me select a different configuration. This made component replacement quick and easy but it has disappeared and I would like to know if there is a setting I may have inadvertently changed and if so where is it?

Pic shows what I'm looking for.

SolidworksConfigurations design Tables