Modern propane tanks have a mass flow prevention valve feature that is designed to prohibit flow if it thinks a leak is present when the tank valve is opened. You may have to start from scratch, that is, all downline valves set to off, propane valve closed, remove hose connection from tank and then reconnect hose connection and slowly turn on the tank valve. Then follow GK2018's process for bleeding the air in the propane lines. You will also need to inspect the flexible gas lines that have been known to crimp closed when a slide is closed. The stove is your best point to ensure gas is flowing.