I have just contacted Microsoft support, who directed me here.
I am trying to create a custom list across colums so each cells value is linked with its adjacent cell i.e. A1 and B1, A2 and B2, A3 and B3 etc...
the idea being when one of these values appear, I can click and drag to reveal their counterpart.
When I try to create a custom list, I get an error message saying "Cells without simple text were ignored" and nothing gets imported as a list...any way around this? I have tried to change the format to "text", "number" and "general" in the home tab but does not resolve the issue.
Custom lists contain static values and apparently Excel does not like it if the cells containing the list have formulas in them. Your only workaround is to first create a static copy of the formulas (paste special values) and then import the list.