Can I make issues or comments private?
There's no way to make a Sifter issue private, however you can create a separate project that only your team can view. Then, if you need to later, you can easily move issues between the two projects.
Sifter does however support "Internal Only" or private comments. Internal-Only comments are available to primary organization users and give your team a way to communicate privately so you can efficiently manage issues and collaborate on solutions.