I'm unable to replicate behavior I see during a testcomplete test by hand

Sometimes TestComplete is running too fast for the application and it will miss something that you can always do because you are always slower.  :smileyhappy:

You can first try putting a Delay in front of the section that is failing.  If you can slow it down and fix the problem, then you have some choices.  One is, you can just leave the Delay in there.  Another is that you can use one of the Wait commands to wait to execute that part of the test until the object in question becomes available.  A third choice is that there is a Project Properties setting under playback that lets you control the time between events in your test.  We have used all of those things in different areas of our testing