"Gain knowledge from an elder" quest can't be completed.

So there is no a clear answer lol maybe I will just wait longer and see if anything pops up ☹️ thanks anyway!

I think there is a cap of only 3 events per day to earn heirloom tickets. If you have a retired sim plus 3 children only 3 out of the 4 events will show up. If you have more sims than the game's limit of events it may happen with other retired sims. I have had 2 retired sims and 3 kids and only got 3 events per day. The kid events will show up before the retired events. 

@Phantomlover1717 I have noticed only 3 events per day . I believe there is a cap. I hope EA staff posts back and lets us know if this is a bug or a 3 event cap per day 

So today the bubble finally pops up, but when I clicked in it’s just normal events there is no mentoring options. Even I finished the regular chaptet option and see if the mentoring option would come but still no.  Don’t know if it is because The 3 cap thingy or not coz i have done 3 already today.

The cake does not count as an event. Only the teaching your kids where you get an heirloom reward count so you got 3 events. Because I only have two kids I got to do a baby and two toddler events.  I did the baby event he then popped out of the bassinet and it then gave him a toddler event too. My other toddler just got his toddler event. 

Glad it popped up. Again this morning I got 3. I retired a sim and still have 2 children

Could you have a peek under the friendly interaction, you would have to scroll down for more option and then choose friendly options. 

Thanks for checking, we have a but report on that issue:
https://answers.ea.com/t5/Bug-Reports/Open-Family-Elder-Event-isn-t-showing-up/td-p/6926345