Hello,
Can you please provide us with a Live URL or the Standard Embed Code of the Mailchimp you are trying to use so that we can check out the exact issue and provide you with a more accurate solution for this. Thanks for your Patience.
Additionally, Canvas already supports the First/last name for the Mailchimp Subscription Forms and this functionality can be achieved by using the following Form HTML Code:
<div class="subscribe-widget subscribe-form clearfix" data-loader="button" style="max-width: 400px;">
<h5><strong>Subscribe</strong> to Our Newsletter to get Important News, Amazing Offers & Inside Scoops:</h5>
<div class="widget-subscribe-form-result"></div>
<form action="include/subscribe.php" role="form" method="post" class="nobottommargin">
<div class="row clearfix" style="margin-bottom: 10px;">
<div class="col-md-6">
<input type="input" name="widget-subscribe-form-fname" class="form-control required" placeholder="First Name">
</div>
<div class="col-md-6">
<input type="input" name="widget-subscribe-form-lname" class="form-control required" placeholder="Last Name">
</div>
</div>
<input type="email" name="widget-subscribe-form-email" class="form-control required email" placeholder="Enter your Email" style="margin-bottom: 10px;">
<button class="btn btn-success" type="submit">Subscribe</button>
</form>
</div>
This will definitely work fine.
Meanwhile, do let us know if we can help you with anything else or if you find any further issues with Canvas.