Trained a regression network and getting EXACT same result on validation set, on every epoch I trained this network from this github.

The training went well, and returns nice results for new, unseen images.

On training, the loss changed (decreased), thus I must assume the weights changed as well.

On training, I saved a snapshot of the net every epoch.

When trying to run a validation set through each epoch's snapshot, I get the exact same results on every epoch.

How can this be possible? What's causing this?
The answer is I was too tired to see I was using the same model for validation every epoch, instead of that epoch's model.

Write good code, and this won't happen to you.