I am working off the same original project file. I have several revisions of the project. I created and added a new component to the latest revision without a problem then I came accross a compatiblility issue when I tried to insert the same connector one revision lower. However, I can insert the connector in the other early project revisions.
I get the following warning
Incompatible part was not assigned
The selected part is incompatible with this object and could not be assigned. Please use the part Selection Dialog to check incompatible criteria.
I went into the component maintenance section of the component library and I selected the Include in BOM box and changed the component status from new to current. I don't have this problem anymore but I don't know what exactly fixed it.