In some circumstances, the Microsoft Malware Protection Engine executable (msmpeng.exe) ‌doesn't allow you to open documents from iManage Drive although the executable is added to the deny list. To troubleshoot this issue, remove msmpenge.exe from the system_hydration_deny_list admin setting available in the admin_settings.yaml file as shown below. 

Example:

system_hydration_deny_list:
- imanagedrive.exe
- searchprotocolhost.exe
- ccmexe.exe