It could also be the format of the card or the spec. No USB 3.0 or ExFat allowed
From the manual (2017)
This unit does not support a USB 3.0 device. In addition, other devices may not be supported depending on the model or OS version. USB devices formatted to FAT32 are supported (USB devices formatted to other formats such as NTFS are not supported).
It reads my 32GB stick without problems.SD is used for NAV only. USB 2.0 stick can be 16gig or lower.
It reads my 32GB stick without problems.
Mazda recommends 16GB's. Good to hear 32GB will work with no problems.
It reads my 32GB stick without problems.
What are the requirements for the USB reader? I tried a 200GB SDcard, and my 2018 CX5 dosent read it but it reads a 8GB USB stick fine.
You may want to check that info again.