Edit conditional formula based on Lookup fields

The "Edit conditional formula" for SharePoint list doesn't seem to work for me for lookup fields. 

I have 3 date fields in SharePoint list say:

• Date 1
• Date 2
• Date 3

I want to hide/display them based on a lookup field called "Category" that has three corresponding items: Date 1, Date 2 and Date 3.  For each of the date fields, I have entered something like:

=if([$Category.LookupId] != 1, 'true', 'false')

This doesn't seem to hide "Date 1" field if I don't select "Date 1" from the dropdown (which is a lookup field).

Anyone experienced this issue or know how to fix it? Could it be a bug?