Webapp installed on Galaxy, OAuth works for browsers but fails for iOS

i have deployed my first app to Galaxy, with OAuth solutions for Facebook, Twitter, Google, and Instagram. i have all of these working for desktop browsers and Chrome browser on my iPhone, running iOS 9.3.2.

please note that this is a webapp, not a Cordova install.

for mobile Chrome, all 4 OAuths work. for mobile Safari, all 4 fail. i get the popup, put in my credentials, the popup goes away, and i’m still at my login screen.

i see nothing in the Galaxy log.

i’ve read that Safari iOS 8 has a window.close bug, preventing this from working. But afaik, if my iOS version is 9.3, then my Safari version is 9.3. i assume, perhaps wrongly, that the window.close bug has been fixed.

does anyone have this config working, or know why mine is not?

% meteor add force-ssl

that seemed to take care of it.