Often on shoots, especially drama, you need to hide your transmitters, but often some people have complained about range issues in certain positions.
This is usually because the body is taking out and blocking the signal being sent. This is also to do with if the antenna of the TX pack is touching the actual skin of the talent. When this happens your radio mic signal range will be impacted.
So next time you need to hide a pack using a wireless mic belt then you can make sure it never touches the skin but adding a ball of tape to the antenna will keep it free and limit the amount of signal lost during transmission.