@hello seems like strange things for a “thief” to take 
More likely ( since the empty box was left ) that the gloves have been used for pet care or cleaning .
Has anyone else ( other than the 5 sitters ) had access to your home ? Cleaner ( other family members ) etc ?
Could the items have been put in a different place ( eg were out on countertop and cleared away while sitter stayed and not put back )
One thing is certain , if the items have been stolen , they were not taken by all five sitters .
There was a recent thread about hosts who suspected that their sitters had stolen things . The items were later found .