[Android] Cloud feature, USB flash drive access

I own two Android tablets. A Samsung Note Pro 12.2 with Android 5.02 and a Nexus 7 (2014) with Android 6.01. I use the cloud feature of CC to load books onto the tablets for reading.

This feature works great on the Samsung with Android 5.02 and I can find the USB flash drive listed under storage and find the Calibre library.

However, with the Nexus 7 and Android 6.01 I can't locate the USB Flash Drive in the storage folder.

Does anyone else have this problem with Android 6.01? Is there a workaround or fix that anyone knows about?

Thank you in advance for your responses.

Regards,

Jim Savitz