Why Doesn't This Button Launch a Modal Window?

I’ve got a page: https://philcata.com/offer-directory/categories/books/

When the viewport is mobile it takes the filters which normally appear in the right sidebar and places them into a modal. When someone clicks on the filter button, the modal window opens showing them the filtering options…but it isn’t working currently. I’m not sure what changed.

The basic button code looks like this:

<button type="button" class="btn btn-primary filter-btn" data-toggle="modal" data-target="#myModal"> <i class="fas fa-filter"></i> Filter </button>

The called myModal looks like this:

 <div class = "modal" id = "myModal">
                        <div class = "modal-dialog p-0 m-0">
                            <div class = "modal-content">
                                <div class = "modal-header">
                                    <h4 class = "modal-title"></h4>
                                    <button type = "button" class = "close" data-dismiss = "modal">&times;</button>
                                <div class = "modal-body">
                                    <?php dynamic_sidebar('offer-sidebar');

The site is built on WordPress and uses Bootstrap. Any hints would be greatly appreciated!