You can try using the FindChild method (with array as parameters for search criteria). I guess you will see by using object browser that old "popup" is still here but 0 sized.
You can also use FindAllChildren to check if Width or Height are > 0
Mapping can cause this kind of issue from my own experience
I had this same issue when upgrading out tests to run in IE11, first of all i needed to map the objects, as they were new objects but for the engine to recognize them i needed to change my project configuration.
I found that adding the following to the accepted windows allowed me to map the save and open buttons
Click Tools and select "Current Project Properties"
Add "Internet Explorer_Server" and "DirectUIHWND"
Please see Screenshot
