Vectored Interrupt Controller causes stuck in alt_tick()

Hi, I am facing issues when using the Vectored Interrupt Controller with the Nios. Sometimes I experience that my Nios seems to crash and when pressing pause during debug I find that the system gets stuck inside the while loop of the alt_tick() function. Does anybody understand what the cause of this issue is? It is weird that if I use the default Nios IIC I will not experience this problem. Any help is appreciated.