I have the same issue. My VP receives interview meeting invites from recruiters. I have an evaluation form that I prep, along with resume and job description. I used to open the meeting invite attach the documents, and in the body of the meeting, would add notes for my VP to prep for call. I no longer have the ability to add attachments, or notes to the body.
Additional problem is meetings that I create and invite from VP's calendar, I would also add the occasional attachment and/or note: John Doe will be 10 minutes late to meeting. I don't want other invitees to see the attachment or not. Until a couple of months ago, I had 3 options when saving the meeting. (1) send update to all attendees; (2) save updates without sending; (3) Cancel, not save. Update 2 is no longer an option and still impeding my work, even after 2 months. I cannot leave notes to my VP in the meeting without sending to all attendees or not saving at all.
Please bring back these features. I have heard from more than enough co-workers that they're frustrated, too, when these features simply disappear overnight.