I might have found the solution to this since I did not get feedback from the support team after raising a ticket
Blockquote
([DAY_WEEK]==3?“TU”:“”)([DAY_WEEK]==4?“WE”:“”)([DAY_WEEK]==5?“TH”:“”)([DAY_WEEK]==6?“FR”:“”)([DAY_WEEK]==7?“SA”:“”)([DAY_WEEK]==1?“SU”:“”)([DAY_WEEK]==2?“MO”:“Cannot be empty”)