Pump doesn't seem to prime

I am not sure if this is a legitimate way to word this problem I have encountered. After my rig sat in storage all winter I got it out and flushed the antifreeze from the lines using city water hook up. Then I cleaned and sanitized the tank and lines. Now I put tank freshener in and I turned the pump on and it runs and runs and runs. I assumed it takes a while to fill the water heater but in the mean time I open the kitchen faucet and nothing, opened the bathroom faucet and nothing, outside kitchen faucet, nothing, toilet nothing. By nothing I mean not even putting out air. Here is the weird part......if I hook it up to city water just to fill the lines and unhook the city water, turn the pump on everything works fine with the pump. Is it possible that somehow the pump gets air locked when everything is drained out and can't fill the lines back up??

Check your valves on your pump, sounds like you have a valve turned wrong. Either the pickup line for antifreeze or one of the winterizing valves at the HWT.

After checking the position of the valves make sure you have the fresh water tank 1/2 full or more. With the city water on... try opening the pump suction valve half way (city and tank supply water) sending city water in the fresh tank suction line to purge the air out.

Must have been air in the line last night. Tonight it worked like normal.