Hello, 2017 W211 (E280) with a strange problem, sometimes and not always when removing the key the dash goes off as it should but the engine stays running. put the key back in and sometimes it senses the FOB and sometimes it does not until it goes back to working properly then all is good. My mechanic said it happened to him and tapped a couple of times below the ignition on the plastic cover after removing the FOB and the car shuts off. Any insights as to what could be wrong? I appreciate your help in advance.