Class modal-dialog-centered does not work on IE 11

[Webdude737]

This might an issue with Flexbox and IE 11. In any case, opening up the modal does not vertically center it.

Easy to Reproduce: In IE11, go to https://getbootstrap.com/docs/4.0/components/modal/ and click on the "Launch demo modal" button in the section "Vertically centered".

IF there is a workaround class or code, please advise. Thanks.

[larrybahr]

I am having the same issue using bootstrap 4.0.0. IE10+ is supported, but .modal-dialog-centered is not working in IE11. @ChVince suggested that it is a known IE11 flexbox bug in #23638

To work around the issue, I changed the .modal-dialog-centered CSS min-height to height (demo).

[peterhpchen]

Thank @larrybahr. It works for me.

[ray73864]

Having the same issue with the modal-dialog-centred, as a work-around I am setting the "top" css rule on the modal.

At first I thought it was just what I was doing, so I loaded the example in the documentation on IE11 and it too had the same problem.