Any update needs to come from Fitbit. Seems there was a recent one but according to their website, the A70 isn't supported. Reading some of the forum comments suggest there's a lot of issues with this app.
We have A70 and Fitbit worked perfectly until the Fitbit app update 3 weeks ago. since then it won't pair or sync. Fitbit help make all the right noises about trying to help - but in reality its the App update thats caused this. Theyve acknowledged they have a problem and say they're working on it - but thats it. Look at the comments about the App in play store. seems Fitbit have huge app problems - just wish I'd researched a bit more before buying!