Does a connected broker account guarantee market data?

No. A connection can be Connected while market data is waiting, partial, or unavailable. Most prop-firm Tradovate logins do not share quotes with apps like Copilink at all. Without quotes, Live P&L falls back to slower Tradovate snapshots, or goes Unavailable if that fallback is off. Copying still works, but P&L-based limits get slower or stop being checked.