After migrating to Bootstrap 4, I noticed that my columns are all vertically aligned. I have updated the boostrap-min.css from version 3 to 4 and double-checked the code for any errors, but everything seems correct.
To further troubleshoot, I used a JS fiddle and was able to replicate the vertical alignment issue there as well. If anyone can provide guidance or point me in the right direction, I would appreciate it. According to the documentation at https://getbootstrap.com/docs/4.0/layout/grid/#mix-and-match, everything should work correctly.
<div class="row">
<div class="col-12">
<div class="col-md-2">
<h1>TEST</h1>
</div>
<div class="col-md-2">
<h1>TEST</h1>
</div>
<div class="col-md-2">
<h1>TEST</h1>
</div>
<div class="col-md-2">
<h1>TEST</h1>
</div>
</div>
</div>
Click here to view the JSFiddle example.