OmniFocus was originally coded up to treat the inbox as a place for items you wanted to remember, but hadn't actually decided for sure that you wanted to work on. Hiding those actions in context view was regarded as a feature, in other words, because it prevented distraction from the tasks you had decided you wanted to work on.
We've been backing off of that gradually over time, but it looks like this is one case where it's still being enforced - if a view is focused, Inbox items won't show in Context view.
We've got a feature request filed on changing that - interested parties should email our
support folks & ask to be attached to that request. (Items with more customer interest tend to get higher priority.)