thanks for the quick respoonse, I highly appreciate this.
Yes, you are right, the priority capping is mentioned in der reference manual, unfortinuatly not in the web site: https://www.freertos.org/a00125.html Good to know, that the website is not as complete as the manual.
However despite the capping is also mentioned in the manual for vTaskPrioritySet() there is that assertion
configASSERT( ( uxNewPriority < configMAX_PRIORITIES ) );
I recommend to add that same assert to xTaskCreate(), too.