You can format your SD card file system to make it compatible with your Mac so that your MacBook Pro will pop up a window to show the SD card files. But you can try some easy solutions first because formatting erases everything on your external hard drive.
Restart your MacBook Pro. Some tiny errors or unknown bugs can be fixed by restarting. Click the Apple menu on your Mac > Click Restart from the dropdown menu. Wait for the Mac to power on, and then insert your SD card into the SD card reader slot gently, then see if the Mac opens a window and shows the files on Sd data automatically. If not, keep reading!
Check the Connection. Poor connection brings the MacBook Pro to reading your SD card in an unnormal way. You can apply an SD card adapter to connect the SD card and your MacBook Pro. If an issue exists still, try to check your MacBook Pro.
Check your Mac's SD card reader. Insert your SD card into another computer device to verify whether the computer can read it normally or not. If it can, then it's your MacBook Pro SD card reader slot fault.
Change your SD card file system. Your SD card files show up normally on your digital camera but don't on your MacBook Pro, it's possible that the file system of your SD card is incompatible with Mac. You can format the SD file system here: Insert your SD card into your Mac > launch Disk Utility > select your SD card in the left sidebar of Disk Utility > Click Erase on the main window > rename your SD card > choose APFS in Format and GUID Partition Map in Scheme.
Ask for the professional help from Apple Service Center. If you're so unlucky encounter the MacBook Pro hardware problem. Solutions from Apple Service Center might be the only fix.
The SD card reader slot hardware issue can only be fixed by repair or replacement. Therefore, ensure your MacBook Pro is still under warranty, and this action can save you lots of money. Then take your MacBook Pro and the SD card to the local Apple Center for expert advice ASAP!
Also read: How to Fix SD card Files not Showing Up on Windows and Mac?
Hope this answer can help you out of trouble!