I'm trying to update an date in a workflow using the Date Interface.
As I need the date to be updated in 10 different formula downstream I'm adding a new column in the Formula tool to hold this date. I can then refer to the new column in my downstream formula.
I've set the format of the new column to be Date and using a dummy value of '1999-12-31'
However, I get an error when running the workflow , so I'm assuming that something needs to be adjusted in data types, or there's something odd in the configuration that needs to be tweaked!
The error I get is:

I've attached a trivial workflow that replicates the error, hopefully it's something easy to fix as I'm hoping to avoid the need to manually type in the Extract date into the downstream formula.