Alerts - No emails are getting sent from questions within collections

We have a customer using the Insight alerts.
She has setup some alters on questions which are in collection as well as few are outside collection.

She informed that questions are within collections, she is not receiving any alerts from those questions even though data meets the alert conditions. Whereas, if she creates the same question and saves it outside a collection then she receives it everytime.

We are using Metabase ver 0.28.6

Has anyone ever seen/noticed this issue?
Is there a way to see the history of all the alerts/pulse emails that were sent?

Thanks for help in advance!

Looking at the setup, I am now also wondering that if there is a custom group and the alert email is expected to be sent to the user belonging to this new group, then does this scenario work for all?
or if anyone has ever faced an issue with this setup?

Mine work fine from within collections (all my questions are in collections). 28.6 is old, can you upgrade?

Thanks Andrew for the response!

Yesterday after running of tests on different configurations, we came down to the fact that alerts were set to fire hourly and refresh was also set to go hourly. So there was an overlap and both were firing at the same time and probably before the refresh finished, alert was either failed or didn’t get any results. Hence, no alerts were sent.

We changed the alert to fire every 65 mins and which resolved the issue.

Do you have any alternate recommendation though on this?