I wanted to reorganize the maps of my old Oregon 600 and reinstall the Garmin Cycle Map from the purchased maps in GE on the emptied SD card. Installation started, but then reported that there is not enough memory - the SD card was not recognized - no dialog to select SD-card.
I then connected the Oregon to my MB-Air M2 - there is still GE 7.20 installed - here the installation displayed the dialog for memory card selection and installed it without any problems.
Conclusion > Garmin Express 7.21 has an error in the detection of SD cards.
Greets, Hubert