Tab-Group Header not displayed

[luminousleek]

Please confirm that you have searched existing issues in the repo

Yes, I have searched the existing issues

Any related issues?

No response

Tell us about your environment

macOS Ventura

MarkBind version

5.4.0

Describe the bug and the steps to reproduce it

In this part of User Guide, there is a code snippet that shows how to specify a header for a Tab-group. However, the header is not there, as seen in the screenshot below.

Expected behavior

The tab group should have a header called "Third tab group 🌌 " for the first tab group and "Disabled fourth tab group" for the second tab group

Anything else?

I reverted the codebase to v3.0.0 to test it myself and it still doesn't work in that version :( So I don't think it's caused by the Bootstrap migration from v4 to v5.