ToDo - Flagged Emails don't open in iOS

Hi all, 

I've been trying to figure this out for a while and it's become enough of a problem that I am hoping someone has a solution.  

I'm using ToDo (v 2.60) and Outlook (v  4.2201.2) on my iPhone 8 plus (ios 15.2.1) and for some reason when I try and open a flagged email in ToDo, I get an Outlook error message "Message not found - No matching message found".  I have confirmed that the email is still flagged in Outlook, and when I try this on my laptop, everything works as expected.  I've reinstalled ToDo and Outlook, but without luck.  

Does anyone have any ideas on what else I can try?

Chris