Custom alert is not working as expected

Summary

Custom alert is not working as expected

Content

Hello experts,

We had created a alert to be sent when learning assignment is withdrawn within 40 days from offering start date and when the learner belongs to certain BU. Here are the filter condition used

${businessUnitName} = 'BU A' OR ${businessUnitName} = 'BU B'

${withdrawnDate} >= ${offeringStartDate}-40

Recipient method is worklist and the expression used are "${AlertUtils.person(learnerLearningRecords.assignedToId).UserName}" and "${learnerLearningRecords.assignedToPersonDetails.lineManagerPrimaryEmailAddress}".

It is on demand alert and running successfully and show count as 4 but no email is received. If any of you happen to know what am I doing incorrectly and how I can fix it, please let me know. Also log shows 4 message count but when I expand, it is blank. Attached are the snapshots.