Only usb device setup is captured, nothing else

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Hi all, I use wireshark with usbpcap to capture the exchanges between a windows 10 laptop and a USB sound card (boss gt1) as I want to try to help the linux driver. I only get the first 4 URBs (device and interface descriptors/configuration) and nothing after even while I am listening to music through the usb sound card or when I change the volume setting. I tried with no filter and I can see URBs for other devices, and I actually I just tested a USB mic and I can see the isochronous URBs in and out (the mic also has a headphone plug), so the setup is at least partially functionnal... What am I doing wrong? TIA Manu