My project include classification of images into several classes.
I'm having a strange issue related to adding mixup augmentation. The accuracy of the training set and the validation set keep rising during all training.
However, the accuracy on the test set improves significantly until epoch 80 (over baseline without mixup - grey), but when the learning rate is reduced it collapses. Note that each 40 epochs I reduce the learning rate.
Is it learning rate/optimizer/scheduler problem? If so..what should I do? I already tried cosine schedulers and linear schedulers.