Configurable Joint Spazzes Out When Rotated

I need a little help from someone more experienced with Configurable joints than I to figure out why this is happening. I'm making a knockdown game in which players throw balls at targets and the targets fall down. I decided to use a Configurable joint for the targets, so they fall down after they are hit. I chose a configurable joint over a hinge joint because the hinge joints were not predictable. A lot of times, the target would end up in some weird position despite it being locked to the X axis and the limits being set (this likely had to do with the speed at which the ball is thrown, but changing that isn't an option).

So anyways, the configurable joint worked, but I just discovered that they start spazzing out if i change the Y rotation in the slightest.

I've attached an empty project (version 5.5) so you can see which settings I have set for the configurable joints. To see the behavior I'm talking about, just hit play and change the Y rotation of "Rail Target" to anything other than 0.

Is this being caused by one of the settings, or is it a bug? If the former, how can I prevent it from happening?

Thanks

Spazzing Joint.zip