What does "usually located" mean in renter's insurance policy?

Had my personal items stolen from rental car while on vacation. Our insurance company is claiming that the following line in our policy applies :

"We cover personal property usually located at an insured's residence, other than the residence premises, for up to $1,000 or 10% of the Coverage B limit, whichever is greater."

My property is not usually located in a rental car? How is this normally interpreted?