Why is Coinbase saying I have 0 balance?

Could you please clarify why Coinbase is indicating that I have a zero balance in my account? I've recently made several transactions and had positive funds in my account prior to this notice. Is there a possibility of a technical glitch or a mistake in the system? Additionally, how can I go about verifying my balance and ensuring that my funds are secure? I would greatly appreciate any assistance or guidance in resolving this issue.