Not really sure about the Readrate message - I've never seen that here. Might be worth to check journal/dmesg if there's some actual problem with the USB drive.
BTW: When posting logs from the console please use the "pastekodi" script. This will also include journal/dmesg which can contain very important info. And also please don't use a mouse, that spams the kodi log with lots of useless pointer move messages and it's very hard to find the actually relevant information.
so long,
Hias