In he "FreeRTOS V9 renesas rx 200 demo" file, the value of configKERNELINTERRUPTPRIORITY is 0, but it must be at least 1 or more. I think that it will not work properly if its value is 0.
This is because the value of configKERNELINTERRUPTPRIORITY is set in Priority Reg of Interrupt of RX 200 in port.c etc. However if the Reg value of RX 200 is 0 the interrupt will not operate.
I will have to check the hardware manual to remind myself. Presumably the interrupt must be executing though otherwise the demo would not function at all.