I am using RA2L1 series and FSP 3.5.0 . As its my observation when I use nearly up to 28 interrupts (weather it is of GPT, UART, SPI I2C no matter) no problem seen, but using new stack, not allowing to enable further few interrupts of same stack.
Do I need to do it manually or its really conflicting?
With the RA2L1, not all interrupt sources can be assigned to every ICU slot, this is a HW limitation. From the RA2L1 HW users manual :-
or another view :-