Hi there!
I've been a proud owner of an Arc since November 2012 and this has me stumped. When I first got it I went and installed all my favorite apps, one of which was Instagram. As it turned out it was incompatible, so I thought no sweat I'll just wait till 4.1.1. Months later (today), along comes 4.1.1 and yet it still does not work.
I've Googled long and hard for a solution and ended up downloading the .apk from
here which claimed that it was Arc compatible, yet when I installed it and tried to update Google Play was giving me the "not compatible" message.
So now I'm stuck with an app that I cannot log in to because I cannot update.
Can anyone with wizard levels of Android knowledge help me out and get this stupid thing to work?