Columns not rendering properly in theme / on site

[respatialized]

I'm having rendering issues. Tailor appears to create the right separation between columns, at least when viewed in the page editor of the dashboard:

But it doesn't actually visually place any of the content blocks into columns when I drag them alongside each other:

The issue persists when saved and viewed outside of the tailor interface.

I'm on WP 4.8.3, with the latest release of Tailor (1.8.1). This issue crops up consistently across a few themes I tested: Twenty Fifteen, Twenty Sixteen, Twenty Seventeen, Hestia, Shoreditch, and Themelia.

[respatialized]

Here are the divs that tailor creates on this page:

<div class="tailor-element tailor-section tailor-5a0750a91450f">
<div class="tailor-section__content">

<!-- tailor:tailor_row:5a0750a91450i -->
<div class="tailor-element tailor-row tablet-columns tailor-5a0750a91450i">

<!-- tailor:tailor_column:5a0750a91450e -->
<div class="tailor-column tailor-5a0750a91450e">

<!-- tailor:tailor_content:5a0750a91450d -->
<div class="tailor-element tailor-content tailor-5a0750a91450d tailor-content--placeholder">

This life, which had been the tomb of his virtue and of his honour, is but a walking shadow; a poor player, that struts and frets his hour upon the stage, and then is heard no more: it is a tale told by an idiot, full of sound and fury, signifying nothing.

</div>
<!-- /tailor:tailor_content:5a0750a91450d -->

</div>
<!-- /tailor:tailor_column:5a0750a91450e --><!-- tailor:tailor_column:5a0750a91450h -->
<div class="tailor-column tailor-5a0750a91450h">

<!-- tailor:tailor_content:5a0750a91450g -->
<div class="tailor-element tailor-content tailor-5a0750a91450g tailor-content--placeholder">

This life, which had been the tomb of his virtue and of his honour, is but a walking shadow; a poor player, that struts and frets his hour upon the stage, and then is heard no more: it is a tale told by an idiot, full of sound and fury, signifying nothing.

</div>
<!-- /tailor:tailor_content:5a0750a91450g -->

</div>
<!-- /tailor:tailor_column:5a0750a91450h -->

</div>
<!-- /tailor:tailor_row:5a0750a91450i -->

</div>
</div>
<!-- /tailor:tailor_section:5a0750a91450f -->```