On my board (with a SAME70), I have a USB CDC driver implemented, and it works well. I use ASF 3.31.0, and arm gnu toolchain 184.108.40.2065
I tried to upgrade the toolchain to the latest version (6.3.1). My project can still compile, no warning. The result hex is not the same size (not the same version of the compiler, so that doesn't hurt me), but the USB device is no more recognized by my computer. Other things still work : a LCD screen for example. I use the same machine, same atmel studio, the only thing I changed is the toolchain.
I also tried to upgrade to ASF 3.34.2, that doesn't help. Same behavior.
Any idea what could cause that?