I installed MainWP on one website (our department specific website) and installed MainWP child on another website.
Then I tried to remotely update a plugin and nothing happens.
Apparently on WPEngine, if I update a plugin, I get a popup notification asking me to either go ahead with the update or make a backup point. See the screenshot.
Please try reaching out to WPEngine support and have them add the nginx rule from the help document that @7thcircle linked to.
Let us know if that helps.
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