Learning Rate Finder runs for a maximum of ONE Epoch by trying various learning rates for different mini-batches in that one Epoch. If your batch size is larger than 5 and you have only 5 images, then One Epoch means run One Batch i.e, one learning rate. So, it results in a one datapoint for the Loss. Since it doesn’t have multiple Batch runs, its not able to Plot the curve on how Loss changes for various Learning Rates.
You can try reducing the batch size (bs parameter) to learner / data object to 1 and see if that gives you a plot (since it will try a max of 5 batches with different learning rates) But for this to be useful, you might need to collect more data. Having a dataset of 32 and Batch Size of 8 might be a good place to start?
When I have problem with finding a good learning rate, I usually start with a rule of thumb of 1e-2 (0.01). But lr_find is the optimal way to find a good starting learning rate.