[BUG] cron can not choose every 15 and 45 mins

on:
schedule:
- cron: ‘15,45 * * * *’

But when I put my mouse on - cron: ‘15,45 * * * *’, it shows that run on every first and 30th minute and it actually runs at 0 and 30 minutes every minute not at 15 and 45 minute.