Custom Switch Functional but doesn't change position

I’m probably missing something simple here. I have a Custom Switch which works (i.e. clicking the switch causes the checked value to change), but the switch doesn’t appear to be checked on the UI.

It was working, but something I did broke it.

Here’s my code:

<div class="form-group inline">

   <div class="custom-control custom-switch">

                            <label class="custom-control-label form-label" for="showFilterHaulDates">Only show Customers with Hauls between specific dates</label>

                            <input class="custom-control-input" type="checkbox" id="showFilterHaulDates" name="input1">

                        </div>

                    </div>