Thanks for the information.At the very bottom of the forum page near the "Start New Thread" icon there should be a "Show Ignored Content" link that you can click. This will reveal all the threads created by any users you may have on ignore. It is undone (all the threads are re-hidden) when you refresh the forum page.
After entering a previously ignored thread, users on ignore will still have their posts be invisible to you within those threads unless you once again click the "Show Ignored Content" link within the thread itself (located just above the reply box at the bottom of the page towards the right hand side of the screen). This is also undone once you refresh the thread.
The current system is very confusing. About half the time, I can see the ignored user's posts in a suppressed manner. But I'm sure there are many posts I don't see at all, because I pick up tangential comments from other users. I have no idea what dictates one or the other status for an individual post.
It would be splendid if there were an option to ignore a user that didn't have a built-in pressure to 'un-ignore' frequently due to missed forum content. I'll try using the Show Ignored Content when I suspect I'm missing an entire thread. But it only helps if you know you are missing something, which by definition you don't know.