I would also really like to stress the importance of this to the LastPass team.
My default browser is Chrome, but I 've been using Safari lately as part of some work I am doing, and I have to say that not having the features of binary support, and especially lacking the ability to set an idle log out time limit, is a pretty high security risk.
I know there are challenges with how Apple updates their OS and often break functionality and backwards compatibility, but it seems from the comments that folks using older versions of the OS (not necessarily Sierra) are having the same issue, and it's been happening for a while.
In addition, the absence of additional features like copying a username or a password is absent, which is pretty disappointing.
I hope this issue can be tackled soon, or at least someone from the team can provide us with an estimate of when this will be addressed.