Get nan loss when training with StripPooling

Hi, there,

I tried to adapt Strip Pooling as 3D and insert to my model, but after about 20-50 iterations in a epoch, I got nan loss.
How you saw this situation? 

What's the risk when run StripPooling? Is it because overflow? 

But it's quite confused that the loss didn't go increase or decrease, but suddenly "nan".

Thanks a lot!