Are these setup using an online webinar tool like Zoom? If yes, it maybe that there is an issue with the sync. Not sure you can see this on reports; think it’s just an on-screen display. 

If you hover over the warning what does it say?

when i click on it , i get the “External calendar Sync warning” . 

Is there any other way I can pull out all the ILT sessions that have this warning?

Thanks
 

There is no report to show this so you’d have to look at each course…

Are you using Connect? The message feels like it’s something related to that...If it is, you would need to check the Connect logs to find the errors..