I never heard from Instagram about why my account was temporarily banned; I don’t think they respond to questions like that. I’ve read that you can get banned for many reasons, some of which look like no reason; they are pretty common evidently. So I can’t be sure why it happened.
Hmm… I admit I’m not an Instagram expert. I only made one post with the plugin, and it had no hashtags, just a short description of the photo. There was nothing there that would get it flagged. I submitted a help request and told them what I thought was going on, how I’d used a wordpress plugin, etc. Later that day the account notice changed to say the ban would last one week. The account is pretty new and only has photos I’ve taken, nothing offensive etc. I never got a challenge required message. 🙁