Thank you for the details, I was able to identify the problem by logging-in onto your search dashboard. By default the plugin searches the currently active blog only, unless specified otherwise.
I've selected the “Use all blogs” option on the Multisite options panel for you on both search instances. Now it should return results from both of your network sites as you expected: https://i.imgur.com/LqX9Hql.pngBest,
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