[larryg276]

I was able to use an external card reader to upload files from my camera SD card to my Tab 4. It connected to the USB port. Can I do that with my Tab S3? I don't think the tablet recognizes the card reader.

More info: when I plug the card reader into the USB C port on my Galaxy Tab S3, I get a message that says "USB charging device. Tap for other USB options." When I tap, the next screen says Use USB to
○ Transfer files
○ Transfer images (says to select if transfer files doesn't work)
○Connect a MIDI device
○ Charge this phone
● Charge connected device

The last option is preselected. None of the other options can be selected. The card reader is only connected to the Tab S3 (SM-T820, Android 8.0.0), not to any other device or power source.

[Tim1954]

Make sure the usb settings are on MTP!

[Rukbat]

Transfer files should be the one you select - and it should be selectable. But the card reader has to have OTG internally, or you'll have to use an OTG cable to connect it. (If the phone can't see the card [which it can't if there's no OTG jumper anywhere], you won't be able to select anything but Charge connected device.)