As you say a lot of people asking this question & not many answers...
I did find this one & do not know if it will help you. As Outlook is not working at the moment anyway for you it is maybe worth a try??
1. Right click the Outlook icon on the desktop and choose Properties. Click E-Mail Accounts, click View or change existing e-mail accounts, and then click Next.
2. In the "Outlook processes e-mail for these accounts" in the following order list, click the Exchange Server e-mail account, and then click Change.
3. Under Microsoft Exchange Server, UNselect the Use Cached Exchange Mode check box. 4. Finish up the wizard.
5. On your computer, search for and delete any OST files
6. re-opening outlook
7. Tools, Send Receive, Send Receive Settings, Define Send Receive Groups, Edit, then checking what folders should be available in the OST. It will also ask you to set up offline folders, so just follow the prompts. This recreates a fresh OST.
8. re-enable cache mode (Tools - Email Accounts - View or change existing e-mail accounts, and then click Next. Follow steps 2-4 above.
9) restart outlook