Same here, I use this functionality a lot to move or copy/paste items (flexible planning), which is now practically impossible beyond the month boundary.
From a UI/UX point of view, this is completely unusable, and the reason why I switched back to the good old Outlook.
Same issue with being unable to change the view to multiple weeks by selecting them in the small calendar (to avoid having the '+X' displayed if a given day has more than 3 items)
Combine this with the fact that split view isn't available in month view, this makes the calendar completely useless now.
(BTW: Help>Feedback isn't available in the new outlook, did report this using Help>Support)