Just a short heads-up: The pivot node has no table spec tab in 2.3 (no idea about 2.3.1, tho). Slightly annoying, as otherwise I could check whether or not I got the pivot order selection right while waiting for workflow execution to progress.
Do you mean the tab is really missing or is there no spec in the tab available before the node is executed? For the latter, I guess, you handle missing value differently (see the dialog). When missings are not ignored, it's unclear if the table contains missing values. This will then during execution appended to the table as additional column, or not. That's why, the spec can't be fixed in this case at configure time. Hope that fixes the problem?