I'm not sure whether this might help... but when this happened to me mysteriously with our Fuzzi Bunz, I ran my whole stash through a "cleansing wash" to remove any residue buildup.

Now, I know what you're saying.... " I follow the washing instructions to the letter and don't use any products that leave residue...." I was the same, but somehow something got built up on the surface that made them less absorbent.

I'm sure you may get other ideas, but this I followed the Fuzzi Bunz recommendations for residue removal and it worked a treat. I now do this approx every 6 weeks just to keep them extra clean. Obviously, check your care instructions to see if any of this is contraindicated for Green Kids...

1. Rinse cycle in plain hot water.
2. Wash cycle in cold water with 1/2 cup vinegar and 1/2 cup bi-carb soda
3. Add an extra 1/2 cup vinegar in the rinse cycle of this wash
4. Run through a final quick rinse cycle in plain cold water (to get the vinegar smell out)
5. Hang in bright sunshine and fresh air!!

Hope this may be of help.