Most SSD Readers only support a FAT32 formatted disk limited to 32GB in size.
On the other hand, I too have had SSD issues unrelated to drive size/format. When in CARPLAY mode connected to my iPhone, the SSD disk in the drive is unrecognized entirely. Whereas, music was playing from the SSD Drive immediately prior to connecting the iPhone. Making that connection, stopped playing music and handed off to the phone entirely. Only when the iPhone was disconnected would the disk in the SSD drive be recognized.