Custom column formula not working

Hi all,

I want to create a custom column using the data from a column called "viewed by" containing either

  • the email of the person who viewed the event
  • nothing (empty) when no one viewed the event

I'd like to have in this new custom column 2 options:

  • no (when no one saw the event)
  • yes (when someone saw the event)

Below the formula I use that is not working

case(isempty([Viewed By]), "no", "yes")

image

Looks like either my formula is wrong or the column is not empty when indeed it is (I also tried with isnull)
Any idea on how to solve my issue?

Thank you!!

Edit:
I thought I was being smart and check if the column "viewed by" contain a "@" as those are email adresses with the formula case(contains([Viewed By], "@"), 1, 0)
No luck, still not working, the output is the same even if the column "viewed by" is emply