You can do it with the PREVIOUS_VALUE() table calculation function - though the line spacing comes out a bit odd in the tooltip, so it can work better just to use a separator on the same line and let it wrap.
Attached workbook shows two variants.
List Values in Tooltip.twbx.zip 160.3 KB
Thanks for the workbook
Your example works, but when I do the same thing, I only get the first entry.
Using Describe... I've made sure that my fields are of the same type in your example.
I've also copied your LastRow detail, but no joy.
What else might be wrong?
Almost certainly the definition of the partitioning for the table calculations. For each of the pills onthe shelves which has a yellow triangle, select "Edit table Calculation..." from the pill's drop-down menu and have a look at how I have set those up. Yours will need to be different, based on the layout of your sheet. If you are new to table calculations, maybe post a sample workbook showing the structure you have - or at least a screenshot showing the measures and dimensions you have on the shelves.