Make a new worksheet, and add 3 extra columns. Fill row numbers to col(A), and random numbers to col(B, C, D, E)
Change the Comments entries of col(B,C,D,E) to aa,aa,bb,bb , assuming these are categorical subgroups. Make a new 3D Waterfall,
==> Waterfall has 4 separate plots at Z, labeled as aa, aa bb, bb because they are NOT regarded as categorical. This graph arrangement cannot be corrected even by setting the "Z Value Source" is changed to "Comments" from "Auto".
In order to support categorical tick labels, must set these settings:
Axis Scale tab> Majora Ticks > Type: By Plot Column Label
Axis Scale tab> Majora Ticks > Column Label: Comments
Axis Tick Labels tab> Display > Type: Column Name or Label
Axis Tick Labels tab> Display > Display: Comments