Account restricted to liquidation only for account over 25k

I have set a paper account with 25000$. A week ago, I discover that its buying power become 0.

The equity has decrease to 24856$ during one day. But the equity is over 25000$ when I liquidate all position. And my current equity is $25,084.61.

Why my buying power become 0 and how I can solve the issue?

Additional info
I have tested different parameter in Configuration > Day Trade Buying Power Check: Block on Entry and Block on Exit. No effect.

In Balance > MARGIN REQUIREMENTS, Effective Buying Power is $0.00, whereas RegT Buying Power and Day Trading Buying Power isn’t null.

Account #: 687261288