Moving items within shared mailboxes makes outlook 2016 crash

Hello Microsoft Community

In our company we use shared mailboxes. All 50 users of our company have one specific shared mailbox synchronized in their local outlook 2016 application. In this Mailbox we receive orders from customers and other information from customers, so the users work very frequently in this mailbox. They edit subjects, the delete and attach e-mails and they move emails from the inbox to subfolders.

Now our problem, which we already have like half a year, is that when a user moves emails to a subfolder inside this mailbox, outlook crashes 90% of the time. so you have to imagine the user having to move 30 e-mails from inbox to subfolder, the user works with an opened task manager so he can move an e-mail, shutdown the outlook process since it's not responding anymore and then restart outlook and do the same 30 times. work which should only take 5 seconds of time takes now 15 minutes of time.

the other problem is that not all users always have the same view of the mailbox, one user can see an edited subject already while another one still has the old subject but that's a minor problem, but we really need to fix the crashing problem and I don't know what to try anymore.

we're using outlook 2016 and Exchange Online.

Did someone also have this problem and knows how to solve it? Thanks!