select-label not work perfectly in collapse

I use select & label with attribute(form-label & select-label) in collapse content as the html code below.

when first time load page finished, click button to toggle collapse content, the form-label not show as expect.

please let me know hot to fix it.

thanks

Expected behavior

Actual behavior

Resources (screenshots, code snippets etc.)

<button class="btn btn-primary" type="button" 
        data-mdb-collapse-init 
        data-mdb-ripple-init
        data-mdb-target="#collapseExample" 
        aria-expanded="false"         
        aria-controls="collapseExample">
  Button with data-mdb-target
</button>

<!-- Collapsed content -->
<div class="collapse mt-3" id="collapseExample">  
    <select class="select" id="select1" data-mdb-select-init>
        <option value="1">One</option>
        <option value="2">Two</option>
        <option value="3">Three</option>      
    </select>
    <label class="form-label select-label" for="select1">Example label</label>
</div>