OH yeah. It's rather annoying.
Say if I switch from the calendar tab to the inbox and I’m in the body of the message, Jaws will sometimes just speak the calendar stuff I was just at. The annoying part is when Jaws does this, the navigation keys won't work. I can arrow up or down or by paragraph or even type if I'm emailing or whatever and Jaws is stuck on this text. In order to get focus properly back, I either have to alt plus tab and then back or maybe a control plus sshift plus tab and back.
That or say if I'm in a calendar appointment and am in the notes section of the appointment, Jaws will again, speak the other part of the appointment window (appt time and or address) or some other text like the associated email account and again, I have to shift tab and then tab back to get proper focus to have Jaws read where I actually am or where I can review what I just typed and so on.
This can happen while I'm in the middle of doing something or if the screen is idle.
I've got the fully installed Office 2016 program on my systems so I don't know if that makes any sort of difference with the Office 365 apps.