I assume that the mic cable has been cleaned with alcohol rather well. Ask the actor if he/she has a latex allergy. It would not surprise me if there was latex in the cable itself. You could
call countryman and ask. Besides that, you could seal the mic cable in some other sort of tape... preferably a cloth tape. Never heard of this issue, but with allergies like they are today anything is possible. We just went peanut free around here due to allergies.