Weird insert issue with BG3.0s?

Jen&Andy06

Sorry I'm not a regular around here, but I was hoping someone might have an answer for me! 

I have noticed that some of my BG inserts have started getting stiffer and curling up.  What the heck?  I am guessing maybe they need to be stripped?  We have a mix of new and used diapers, I think it is just from the older inserts.  I know that microfiber can hold stuff in, but they don't smell, and nothing else seems obvious to me that could be the issue. 

How would you strip a load of just inserts?  Or is there something I should soak them with in the bathtub or something? 

Thanks!