Unknown CSS transition delay

I am trying to animate the max-height of the ion-card on click, the card opens properly according to the transition properties set in the CSS, but while closing the card, there is unknown delay of about ~500ms.

Steps to reproduce:

  1. See the plunker http://plnkr.co/edit/1a7912HanqSrHfpX98IG?p=preview
  2. Click on the “Click me” in the card header to see the hidden content
  3. Click it again to close the hidden content and you will see the delay

Which Ionic Version? 2.x

Ionic info:

    Gulp version:  CLI version 1.2.1
    Gulp local:   Local version 3.9.1
    Ionic Framework Version: 2.0.0-beta.7-201605271904
    Ionic CLI Version: 2.0.0-beta.25
    Ionic App Lib Version: 2.0.0-beta.15
    ios-deploy version: 1.8.6
    ios-sim version: 5.0.8
    OS: Mac OS X El Capitan
    Node Version: v5.1.0
    Xcode version: Xcode 7.3.1 Build version 7D1014

I met the same issue: a delay before the transition starts and the max-height goes to zero.