File column shows when "Show?" expression evaluates false

[thethunderbird]

Columns with TYPE “File” show when an expression in the SHOW? field evaluates to false. In this case, I have entered the expression FALSE in the SHOW? field and you can see that the file icon still shows (and I can click it to open the file):

I also tested with ISNOTBLANK(LIST()) and get the same result. If I uncheck the SHOW? box (instead of entering an expression), the column is properly hidden.