Can not turn cobwebs into string

In the past prior to previous updates and adding new content I was able to make string from cobwebs.  I play in Survival/Peaceful mode as I like to explore without having to constantly battling so when finding cobwebs I use my shears to harvest them then take them to my crafting table to make string but when placing the cobwebs into the crafting table I get no string.  Why am I no longer to turn cobwebs into string?