We are encountering a sporadic issue with resume from sleep, where USB devices go missing. (e.g. cannot connect to them, and cannot see them on lsusb).
This happens to us with different devices, the most important for us being a Telit Modem which cannot be used after resume from sleep.
This happens about once every 100 sleep cycles.
A reboot is needed to fix this.
I will attach a dmesg output soon.