Solved by Nikronic in post #2 
              
              
                Hi, 

Your input will be something like this for concatenation: 
x = [torch.randn(1, 32), torch.randn(1, 196)]

So based on this line, I expect the desired out is [1, 196+32]. 

Based on this, you need to concatenate in second dimension not first. First one is for batch size. 
So, this will solve th…