I created a collapse with multiple targets in an accordion-style setup (set data-parent).
The switching works well, exactly once.
The second group of targets then has the show class removed and never added again (only after page reload

Steps to reproduce

Check the codepen sample below and click the numbered collapse links from 2-3, then click on 1 again.
The second group switches perfectly when clicking 2&3, when clicking on 1 again it fails.

environment

• Operating system and version Linux (Manjaro, Arch-Based
• Chrome Version 62.0.3202.94 (Official Build) (64-bit)
• Example, based on he official docs: https://codepen.io/sweisgerber-dev/pen/mqqBbK