I had problems like that earlier this year, on my IT 250H. I was using yamaha filters, and after the 3rd got a unifilter one.
I was told it was due to using too hot a water with the no toil oil and cleaner, but it did not happen to my twin air YZ one done at the same time.
I got the shits and won't use Yamaha filters anymore.
No real help, other than it may the the brand of filter.
Cheers
Kim