shortcode in excerpt attribute no longer working (v1.8.5.4)

On multiple pages I have placed a shortcode within the except attribute. The purpose is to show a short menu until clicked to expand, then it shows a long menu. It has been working fine for years, until recently when the content of the excerpt is now displaying the source html code instead of outputting the list of links. I am upgraded to the most recent version of the plugin, 1.8.5.4. The shortcode on one of the pages looks like this:

[expand title="View Full List" swaptitle="Condense List"  trigpos="below" excerpt="%{%widgets_on_pages id='Themes and props subcategory short menu'%}%" excerptpos="above-trigger" swapexcerpt=""][widgets_on_pages id="Themes and props subcategory full menu"][/expand]

Do I need to adjust something in my shortcode to get it working again?

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