Bonjour
I have two testers on the project and would like a custom field "Tester" (not Assignee, which stays reserved for the Developer) updated whenever one of them transitions issues from Ready for testing to Testing status. I could simply be setting the field to a fixed value, but I'd like it to be updated by whoever initiated the transition.
So ATM my rule looks like that

I've tried using smart values but to no avail. Audit log says:

Any ideas what could've gone wrong?