Impeller issues

Hello all. Yesterday I took my boat (2012 MB Sports B-52 23V) out of storage, installed the batteries and returned to service. I replaced the impeller with a new kit and then brought to the lake. I started it up at the launch and all seemed fine, so after about 5 minutes we left the launch. About 5 minutes later then alarm sounded and the motor went into limp mode. The temp was approaching 200 and I figured the impeller must not be drawing water. I let it rest a while and then idled to the marina. I removed the impeller and it was dry, but couldn't find any reasons why it was dry. I inspected everything, reinstalled, and then ran again but still no water going through impeller. I have a PCM EX 343, and the raw water inlet runs through the transmission, then to the motor. Is it possible that it is cavitated since the block was empty from winterization? I know it is usually empty after winterization so I can't imagine that is the issue. Any thoughts are appreciated.