css transition not working in mobile chrome

After a few days of searching what actually worked for me is just Chrome restart.

Please also add/keep -webkit-transition: transform 200ms;. So in the end you should have:

.checkmark {
    width: 35px;
    -webkit-transition: transform 200ms;
    -webkit-transition: -webkit-transform 200ms
    transition: all 200ms;
}

.checkmark.scale {
    -webkit-transform: scale(3);
    transform: scale(3);
}

See it here working with mobile chrome (iOS): https://codepen.io/miikaeru/pen/aMXYEb