Inspiron 17R 5721 running Win 10 Pro, x64.

Once I use the Safely Remove icon on the taskbar to eject a (Samsung) SD card, I can no longer use the icon to eject a USB2 flash drive. If I reinsert the SD card, it's recognized again, but now it also cannot be ejected using Safely Remove.

If I open This PC window, both the SD card and flash drive are listed and both can be ejected by right-clicking and selecting Eject.

If I don't insert the SD card, the flash drive can be ejected, reconnected, and ejected multiple times using Safely Remove. So there's something about ejecting the SD card.

After rebooting, Safely Remove works again, as long as I don't eject an SD card.