Custom Alert is not triggering daily though scheduled to run daily x 1 once

Hi Experts,

We have an 'Alert' scheduled to run daily to send notification to line manager when their reporting team members work anniversary is = 3 days, however when I verify in the alert history though we have scheduled it to run daily, it has skipped to run on 17th Feb,18th Feb, 19th Feb

Similarly, 23rd, 24th, 25th Feb due to which it missed to notify line managers.

Any thoughts/advise if someone has experienced this before and what could be a possible solution to fix it to run daily including weekends/holidays. Thanks in advance!