This is something I have complained about before... showing me "failed" great.... but we need a reason why the schedules failed.
However, there is a current bug... don't trust the failed display here... for the last few months the "failed" area is showing ALL reports, whether they fail or not! You can see this clearly... you have 22 Scheduled Projects, and 22 "Failures"... This is logged with the Engineering team, but I have no updates at this time....
I actually suspect that your issue is not that the report has failed, but possibly your work has flagged those emails as potential spam and is blocking them at the server level.... (this is the most common issue I have experienced)
As a test, try adding a personal email (like a gmail or outlook, etc) to a schedule and send it... I believe the "failures" is more like the entire schedule fails... I don't think it will display failed if one email fails.... (but it's hard to say since this failed list has had a lot of issues... initially, reports that actually failed didn't show up at all... and now they show total failures when everything is working... so I'm not so trustful of this list )
It shouldn't matter how many accounts your email is tied to... email functionality should be basic... take the email associated to the account and send the PDF to it....