configKERNEL_INTERRUPT_PRIORITY should be 255.
You say you got that configuration from Arm - can you give more detail? Was it shipped in a CMSIS pack, or with an IDE example, or somewhere else?
If the number must be 56 (why 56? seems a bit random) then don’t use all 56 priorities. For example, if you only need 5 priorities, then use priorities 0 to 4, not 0, 10, 20, 30 and 40.