This weekend I added 8 Kasa KS 200 switches. The Kasa App has been excellent!
After adding devices - I used the system 'swap devices' .. however each time I tried, there was no entry in the list for any of the Kasa switches.
I did try refreshing the page, but unlike other places in HE where sometimes you bang on 'Update' in the drop down or 'Refresh' usually below the pick list, there is no option in Swap Devices' to force it to repoll the list.
I needed to go old school and manually add the device to all the 'In Use By' stuff and hand remove the old devices.