When I edit the format and switch from text to list, I get the following error message:
"Format of mapping used for lookup doesn't match any dimension of the source."
How do I fix this?
That error indicates that the line item which format you are attempting to change is being used / referenced by other line items, and the new format is not accepted by the formulas downstream.
If you go to the blueprint of the module where the LI is, and scroll all the way to the right, you will see the last column of the blueprint called "referenced by", which includes a list of all the modules.line items or list.properties that reference to this particular line item.
at this point you can either cut out those formulas until no other line item or property reference the one you wish to change, then change the format to list and then past back the formulas where they were. Some formulas wont work anymore and you will have to either change the format or the formula of those downstream line items