Why is Hank Gutstop is missing?

Though the notes did not seem to emphasize it much, it's important to note that Hank is missing.

I can't tell you anything else now but the episode connects to the next two - thus, three straight episodes deal with the same subject. 

Even when Mis' Keller and Harry Feedburn were getting chummy, we didn't have three episodes in a row on the same subject (1944 seems to be the year we have the most information for the series, both audio-wise and note-wise.  All the remaining two months of notes are about 1944.)

I haven't looked at it that closely but we may have a near complete log of 1944 before it's over with.