As the title says, in the current beta, the new transparent controllers (in my case index controllers) don't show up in the calibration mirror (calibration mirror is set to transparent). The trackers are set to use the system default design.
That is quite an annoying regression, as I have slight scoliosis, and I use my hands (in the mirror) to align my body correctly to the avatars body. If I don't do that, the tracking is slightly off.