Very often when I try to access the "Rebase children ___ interactively" in the context menu for commits, the option is grayed out for no reason. Simply navigating to a different branch and back makes the option come back. Here's a GIF illustrating the behavior:

I'm not in the middle of an existing rebase. I'm not in a locked state. There should be no reason for this option to be grayed out.

This only happens on SourceTree 3.0.8 for Windows. I've never run into this on the Mac version.