No, this should not be the case. ent_playloop updates the entity and camera position.

Check your acklog. Some old audio driver had an issue that 3D sounds didn't work properly. In that case you'll get a message like HEADRELATIVE in your acklog, indicating that the engine attempts a workaround.

Another possibility is that your camera was not moved at all because you were using a different view. Look for the AUDIBLE flag in the manual.

Apart from that, I can not confirm any problems with 3D loop sounds of moving entities.