Two groups:
10 gal tanks, 1.2 each.

My females dont seem to be taking good care of their babies. Usually they will have about ten and within a week or so all the babies will be gone. One of my girls had ten babies late October, they were all doing well and growing. The other day I came home from school and they are all gone!
I have had two littlers that grew old enough to separate from the mothers, Only about 5 from each lasted. I put the weaners into a 20 gallon tank, they did ok for a while, but then they started being killed off by siblings. I would find just hides of baby rats. Today I check on the four that were left, two are dead on the ground with just their skulls and brains removed! It was awful.
I use dishes for their water, and feed mazuri rat food. I give them honey nut cheerios on occasion as a treat. I keep them on pine bedding.

Does anyone see what could be going wrong? Im so frustrated. All my girls have given birth at least twice and nothing changes. Do they just need a bit more time?

Thanks for your time, please let me know if you have any tips!
Sam