This is a great add-on and I consider it an essential tool for Instagram use....but sometimes Insta updates their code and the add-on breaks. Most recent update (1.3.8) seems to work OK for now.
[update] July 10 - one other reviewer stated an issue with warnings from Insta "We suspect automated behavior on your account. To prevent your account from being temporarily restricted or permanently disabled..." I also received this warning earlier today, and now my Instagram account has been suspended. Suggest if you get this warning, disable this extension ASAP, see if it helps.