Well, one basic indicator is whether you can overfit your network on a (very) small training dataset. If you can’t get it to overfit, i.e., get a training accuracy of 100% or close to, then your network is not training. Most likely because of some issues in your code.
Do you have a Github link or something to have a look at your code. If it’s not to much, maybe you can post your code here. The important parts are usually the model (with the forward method) and the training loop.