[Bug] RTMPose 3D visualization broke in the last commit

[FBarrca]

Prerequisite

• I have searched Issues and Discussions but cannot get the expected help.
• The bug has not been fixed in the latest version(https://github.com/open-mmlab/mmpose).

Environment

The latest commit in the 3D visualization code (local_visualizer_3d.py) has introduced an issue that breaks the RTMPose 3D pipeline.
Reverting to the previous commit (Dev 1.x) resolves the problem.
Please investigate and address this regression.
The issue only appears when multiple people are on frame, as the latest commit changed how this was handled

Reproduces the problem - code sample

https://github.com/open-mmlab/mmpose/tree/main/projects/rtmpose3d

Reproduces the problem - command or script

Just using the code there.

Reproduces the problem - error message

Sorry I dont have this on hand.

Additional information

No response