USB and L4 discovery board
Sorry I did not find a solution yet. Unfortunately nobody from ST chimed in. I always planned to use it with another IDE to see if that cure the issue. Though I do not have access to one at this moment.
When using an external crystal did you make sure that the USB is driven @ 48MHz?
Maybe there is a reason why ST does not offer a working example for this discovery board. Who knows 😉
Mat