@MichelyWeb thanks for reporting the issue. The fix is out now, just released in Pinegrow 7.71.
A background story:
The Loop and Show Posts actions have the option to show a selected element in case the query doesn’t return any posts.
Up to now, the WordPress actions on such “no posts found” element were not processed. For example Include Template Part action was simply ignored.
In Pinegrow 7.7 we enabled action processing for this element, but a side effect broke the theme export (as you have discovered).
So, in Pinegrow 7.71 this feature was rolled-back and actions are again not processed. But, we do display a warning message and suggesting a workaround of using php code directly on the element (in the source HTML project).
Example of the workaround:
...
<div class="no-posts">
<?php get_template_part( 'template-parts/no-results' ); ?>
</div>
All the best!