It happens.
Also if the casings are not fresh, they are prone to not sticking to the finished product. I have some I know are old and I am still using them. I just plan on pealing the casings off after the stick are done. Other than that I see no point in tossing them. I seem to recall one way to check for freshness of collagen casings is to rub them on a sheet of paper. If it leaves a slightly oily mark, they are still good. If it does not, they will be prone to not sticking to the meat.
And Dave O. is absolutely right. Mix until you think it's over mixed (but be careful if using ECA as you don't want to break the capsules open).
So I think I figured out what is causing my issue. When I pulled my last batch of snack sticks the casings were pretty stiff/hard. Like they were dried out from the cooking process. I let them sit in the fridge for a day before packaging and freezing, and the casings softened to what I would call normal.
Here is where the problem comes in. When I pull a pack out to thaw it sends like the casings really soften and stay to pull away from the meat. This gets worse the longer I let a pack sit in the fridge after opening.
Now that I think I know what is causing it, what the hell do I do about it?