a tab with unsent or un-bumped lines cannot be closed
Something on the check is NEW or still 🔥 cooking. A part payment is fine any time; the final tender waits for the kitchen to bump every line, so a table never pays for food that never came.
Send what is new, or ask the kitchen to bump, then take the last tender.
Related: Send, and what the kitchen sees · Start, strike a line, BUMP