Birthday calendars NOT showing only on my iPhone.

Birthday Calendar events not showing up in iPhone Calendar.

1. I made sure i checked it in Calendars list in Calendar app.
2. in Settings icloud, calendar and contacts are enabled.
3. in Settings calendar, Sync all events. also alert time for birthday is at day of event 9am.
4. I read from someone to enable cellular for both contacts calendar and contacts. they are both enabled wan and cellular
5. I can see birthday calendars in icloud.com

I get birthday alerts and I can see them in calendar from my other devices like my ipad, watch, and macbook. Only in iphone it doesn't show up and no alert. i thought it's just bug in one of the updates but Im having this problem for so long until now it's not fixed. And im updated to the latest software update everytime.

Lastly, of course, i restarted my iphone a couple of times.

I hope I can finally solve this. Appreciate all the help.