Field connector not working with Simple Image field when inserting into html

Beaver Themer recommendation for ACF is that you can insert an image shortcode into an img src html statement. Here's what they say to do:
<img src="[acf-field-shortcode-goes-here]"/>

Trying to do that with a MB for example:
<img src="[wpbb post:meta_box field='hover-image-' image_size='medium']"/>
results in "Array" instead of the image url.

1. Can MB images be inserted into html fields?
2. This is actually trying to debug a problem with using a MB custom field image in a Beaver Builder post grid. The standard code for the posts module is:

[wpbb-if post:featured_image]
<div class="fl-post-image">
[wpbb post:featured_image size='medium' display='tag' align='default' linked='yes']
</div>
[/wpbb-if]

but I want to swap out the featured image with a MB custom field image instead, e.g.

[wpbb post:meta_box field='hover-image-' image_size='medium']

so the resulting code would be:

[wpbb-if post:featured_image]
<div class="fl-post-image">
[wpbb post:featured_image size='medium' display='tag' align='default' linked='yes']</div>
[/wpbb-if]

but that doesn't work. Instead of an image I see the word Array instead. So essentially the same issue as #1 above. How do I upload or choose an image file from the Media Library to a Post MB field and then display that image in straight html or the Custom Post Layout in a BB Module?