re: I tried with both Connections network activated and locally activated.
You should not network activate Connections. ONly activate it on the subsites using the plugin. But that should have no effect of the site’s URL has a trailing slash or removing it from Yoast.
re: Any thoughts?
There’s only two areas in Connections where there is code that even remotely affects a site’s permalinks. Connections adds it own URL rewrite rules so the directory links will work. But that only adds new rules, it does not overwrite any core WP rules. Connections does filter the core WP get_permalink() function when viewing it’s directory pages so the function will return URLs to work with the permalink rules it adds.
If you can give me a login, I will edit the code in Connections so the filters for these two items are not run so we can see if one of these are somehow causing the issue. At this point I do not see how, but hey, I’ve seen weirder things. The edit will simply be commenting out a few lines which add the filters that in turn run the code. Without the filters, the code is never run. It’ll break Connections as none of the links will work.