Recently in my one of the MVC Project, dynamically loaded content on Bootstrap modal client side validation was not working. By any chance if you face same issue this post is important for you.
How to resolve
The form is not added to the page when the page loads, so the unobtrusive validation will not pick it up. There are two ways to fix this.
Manually register the form with the unobtrusive validation after adding it to the page. Something like $.validator.unobtrusive.parse("#id-of-the-form");
Hope this helps.