After updating my project's SDKs (base and avatars) to 3.8.0 via VRC Creator Companion physbones completely ignore realtime component tweaks while in play mode. Tweaks to any settings (pull, spring, gravity, immoble, limits, etc) are not respected and physbones continue to use settings only set previously in edit mode. This completely removes the ability to tweak and observe results in realtime.
Reverting base and avatars SDKs back to 3.7.6 fixes the issue.