Is the a min read/write speed when using cards? I have both slower and faster cards but the drive is only reading the faster ones. Any idea what the deal is?
The read write speed may vary according it the environment condition.
Refer to the information mentioned below to know about the read write speed.
Built-in SD Card Reader:
A built-in SD card reader with up to 65MB/s** read speeds
and one-touch copy button makes it easy to quickly
back up photos and videos from an SD card without a
computer or additional software.
Fast SSD Transfer Speeds:
Enjoy fast access speeds and transfer rates (up to
390MB/s read) when using the USB 3.0 port to move
files to and from PC or Mac computers.