It was in a function that is between a undo-able. (Actually, it's in a function (0) that is called by a function (1) that is called by a function (2) that is called by a function (3) that is inside undo-able).
But this set-up is okay with 3012.
~ReignBough~ ARCHICAD 24 INT 4018 FULL (from AC18) Windows 10 Pro, Intel Core i7-4790 CPU @ 3.60GHz, 32.0GB RAM, 64-bit OS