USB RNDIS stucks on STM32H735IGT6

We have a problem converting our running USB VCP application (RTOS) to a working RNDIS version.

• We replaced the regular variants of usbd_cdc.* and usbd_cdc_if.* by their RNDIS variants.
• The USB OTG HS clock is enabled.
• We adapted the initialization:

 if (USBD_RegisterClass(&hUsbDeviceHS, &USBD_CDC_RNDIS) != USBD_OK) {
 while (1) {
 }
 }
 hUsbDeviceHS.pClassData = USBD_malloc(sizeof(USBD_CDC_RNDIS_HandleTypeDef));
 if (USBD_CDC_RNDIS_RegisterInterface(&hUsbDeviceHS, &USBD_CDC_RNDIS_fops) != USBD_OK) 
 {
 while (1) {
 }
 }
​

• We adapted the device descriptor (bDeviceClass=0xef instead of 0x02 and bDeviceProtocol=0x01 instead of 0x00)

The USB transfer is working for 1-2 seconds, but at the end the code stucks with an ISR queue overflow error.

Did anyone ever hear about such a problem? Or what do we miss in our initialization?