AnimDynamics creating space between bones?

I’m trying to use the animdynamics modifier to create tail physics on a fox tail. The rig is set up just fine, but when I use the animdynamics node with the “chain” dynamics ticked, the tail stretches out between the bones, instead of just bouncing and rotating. I feel as though I’m missing some constraint or something but I’ve read so much documentation and tried so many things-- nothing wants to work. I’ve tried just about every setting in the “animdynamics” node with no luck.