How to view monthly bills for each serverless instance?

I am currently running multiple serverless instances at the same time, and I need to see how much each of my serverless instances costs in a month (or day, week) so that I can balance my priorities in the development process. I found the “Billing” section in RunPod, and scrolling down, there is a “Billing Explorer/Runpod Endpoints” section as shown in the picture, but it does not display anything (even though I have spent over 300 USD on RunPod in 2 months). May I ask why nothing is showing up, if I did something wrong, and if there’s any other way to check the bill for each serverless instance?

Any answers would be greatly appreciated; please provide your information