Removable Storage tab not available when in Express

My 750i shows sd card in MS 10 File Explorer, on BaseMap, and in Express under utilities. When I do an update to TopoActive, no "Removable Storage" tab is showing and the warning to make room shows but is NOT showing an sd card as option. My camera and Birds Eye info writes and reads to sd card but not Express. Here are the pix: 

    

This is the third sd card (current card is Samsung 32 EVO Plus) I've tried plus two different PCs with Win10 and fresh up-to-date Garmin Express  V 7.9.1.0 AND followed online instructions to add sd card. The 750i did several updates including City Navigator but fails with TopoActive update. How do I get my 750i to recognize sd card so I can get my map updates? Is there an option to manually move the map set from device to sd card? I searched forum, Garmin, online and did not find an answer to my issue...frustrating! Cheers, J