Hello and welcome @Frederik_van_Dierme1!
Looking at your formula I believe you are missing the DATETIME_FORMAT()
for the Project deadline in the “true” evaluation of your IF()
statement.
I believe the formula should look like the following:
IF(
{Execute day (before/after)}=BLANK(),
DATETIME_FORMAT({PROJECT DEADLINE}, ‘D-MMM-YYYY’),
DATETIME_FORMAT(DATEADD({PROJECT DEADLINE},{Execute day (before/after)},‘days’),‘D-MMM-YYYY’)
)
Let me know if I can help provide any more information, and if this helped answer your question please mark it as the solution :white_check_mark: .