Does the SD card reader show up in the System Profiler report? Here's an excerpt from the following article the applies:
About the SD and SDXC card slot on your Mac - Apple Support
Can I use macOS to see the specifications for the interface hardware and media inserted in the SD card slot?
You can get information about the interface hardware and the media that you inserted in the slot from the System Information:
- Choose Apple menu > About This Mac.
- Click System Report.
- In the Hardware section of System Information, select USB.
- In the list of USB devices, select Internal Memory Card Reader to access information about the interface hardware and the media inserted into the SD card slot.