Switched from Blankets to Straw now they won't use their boxes

So I finally got some straw online from a great company. The straw is soft, smells sweet, and should help keep them warm, yet they refuse to sleep in it? It's currently been snowing every 2 days and gets really cold out. I tried to lure them in with treats, but one of the kittens went in 1 of the 3 boxes to find the treats then ran right out. I switched the straw in on the 18th. Usually after 4 days they'll start using the boxes again after I've messed with them, but they won't even look inside.

How can I get them to want to be inside? It seems like the texture of the straw startles the kittens. The older cats don't even look at the boxes anymore.

Some cats find straw to be uncomfortable, although it is better than blankets.  Are they sleeping somewhere else that's warm?  If not, try a little catnip.  I wouldn't put treats or other food in the straw as that may attract other critters.

If you can afford to wash the blankets often, then I'd put a blanket on top of the straw.  Changing them every day or two will help keep them dry.  When they're washed and dried, put them in the shelter fresh from the dryer.  It  will help warm up the shelter.

They have cheap fleece blankets at Walmart that make it a little easier to buy multiples, allowing you to change them more often.

I'm doing that now! I think they'll like it a lot more like this. Thanks!