@ David
I’ll have to add this to the plugin conflicts.
This can happen when a plugin sets a specific page priority when adding their admin page. If a plugin happens to be in that spot, assigned by WordPress, it will get bumped from the menu.
My experience, it is better to let WordPress manage the priority because defining then only causes issues like this. A quick look thru Master Bar’s code … they add the page with a priority of 100. Which seems to unfortunately be the position Connections occupies (I do not define a priority, I let WordPress assign it).
If you want to use master Bar, you could edit the plugin to remove the priority then things should play together just fine. I found it right here:
https://plugins.trac.wordpress.org/browser/master-bar/trunk/admin/options-init.php#L607
You would remove the 100
leaving just the quotes.
Hope that helps!