Thanks Jamie for the info. I replaced code, but it's now showing the thumbnail as a url. I've also attached a screen shot of the updated invoice showing the url.
Below is my updated code.
<p style="float: right; text-align: right;">
{{ "now" | date: "%m/%d/%y" }}<br />
Invoice for {{ order_name }}
</p>
<div style="float: left; margin: 0 0 1.5em 0;" >
<strong style="font-size: 2em;">{{ shop_name }}</strong><br /><br />
{{ shop.address }}<br/>
{{ shop.city }} {{ shop.province_code }} {{ shop.zip | upcase }}<br/>
{{ shop.country }}
</div>
<hr />
<h3>Item Details</h3>
<table>
<thead>
<tr>
<th>Quantity</th>
<th>Item</th>
<th>Tax</th>
<th>Price</th>
</tr>
</thead>
<tbody>
{% for line_item in line_items %}
<tr>
{% for line in line_items %}
<li> {{ line_item.product.images.first | asset_url | replace: "static", "cdn" | replace: "assets/", "" | replace: "?", "" | replace: "//", "/" | replace: "http", "https" }} {{ line.quantity }}x {{ line.title }} for {{ line.price | money }} each </li>
{% endfor %}
<td>{{ line_item.quantity }} x</td>
<td><b>{{ line_item.title }}</b></td>
<td>{% for tax_line in tax_lines %}{{ tax_line.price | money }} {{ tax_line.title }}<br/>{% endfor %}</td>
<td>{{ line_item.price | money }}</td>
</tr>
{% endfor %}
</tbody>
</table>
{% if transactions.size > 1 %}
<h3>Transaction Details</h3>
<table>
<thead>
<tr>
<th>Type</th>
<th>Amount</th>
<th>Status</th>
</tr>
</thead>
<tbody>
{% for transaction in transactions %}
<tr>
<td>{{ transaction.gateway | payment_method }}</td>
<td>{{ transaction.amount | money }}</td>
<td>{{ transaction.status }}</td>
</tr>
{% endfor %}
</tbody>
</table>
{% endif %}
<h3>Payment Details</h3>
<table>
<tr>
<td>Subtotal price:</td>
<td>{{ subtotal_price | money }}</td>
</tr>
{% for discount in discounts %}
<tr>
<td>Includes discount "{{ discount.code }}"</td>
<td>{{ discount.savings | money }}</td>
</tr>
{% endfor %}
<tr>
<td>Total tax:</td>
<td>{{ tax_price | money }}</td>
</tr>
{% if shipping_address %}
<tr>
<td>Shipping:</td>
<td>{{ shipping_price | money }}</td>
</tr>
<tr>
{% endif %}
<td><strong>Total price:</strong></td>
<td><strong>{{ total_price | money }}</strong></td>
</tr>
</table>
{% if note %}
<h3>Note</h3>
<p>{{ note }}</p>
{% endif %}
{% if shipping_address %}
<h3>Shipping Details</h3>
<div style="margin: 0 0 1em 0; padding: 1em; border: 1px solid black;">
<strong>{{ shipping_address.name }}</strong><br/>
{% if shipping_address.company %}
{{ shipping_address.company }}<br/>
{% endif %}
{{ shipping_address.street }}<br/>
{{ shipping_address.city }}
{{ shipping_address.province_code }}
{{ shipping_address.zip | upcase }}<br/>
{{ shipping_address.country }}
</div>
{% endif %}
<p>If you have any questions, please send an email to <u>{{ shop.email }}</u></p>
