In Exchange 2016 there is currently another error that also occurred in Exchange 2010.
If you run Outlook in cached mode, as Microsoft recommends, and want to move a folder to a subfolder in which a folder with the same name already exists, it will be renamed, e.g. from Test folder in Test folder(2).
However, this does not work in online mode, e.g. with shared mailboxes that are integrated in online mode. Here you get none Error message and the action is simply ignored.
This behavior can also be observed in OWA. However, you get an error message in OWA „The folder couldn’t be moved or copied. A folder with the same name might already exist.“ This is in the KB2717453 Article from Exchange 2010.
As it turned out, the fix was never adopted in Exchange 2013 and was therefore only implemented for Exchange 2010. No one in Exchange 2013 has noticed this over the years and it was therefore not adopted.
The issue has been escalated internally in the product group at Microsoft and is expected to be fixed in one of the next CUs. It remains to be seen whether it will only be fixed for Exchange 2016 or also for Exchange 2013.
The fix was not yet implemented with the last Exchange 2016 CU 14 from September 2019. Let's hope that Microsoft solves it in the next CU.