Trouble-shooting 101 states that if something was working before you made the change, then the problem obviously lies where you made the change. In this case, the change is your washing process.
First off, you should be using some type of "free and clear" type soap. That's the soap with NO anything in it but soap. No scents, dyes, softeners or anything else that could screw up the towel. So there's where I would start. Change the soap you are using. Another thing to do is to MAKE SURE that you are using the correct AMOUNT of soap. It sounds like you are using way to much and the towels are not coming clean. You are probably using towels that are still dirty because they still contain soap and that really screws up the fibers. I outline all of this along with my washing process in this video.