SharePoint OneDrive file sync issues when users open the same file

The issue seems that you/we are using local copies of the documents.  If two people open the same document at the same time, then make changes there will be a conflict.  We too are struggling with this as we have over 100 people using Sharepoint and syncing via OneDrive.  I know you can go online to the portal and "check out" a document but that doesn't fly with our setup.  End users want to use the local versions of Office and not the web client. 

On top of all that, changes are only synced when you CLOSE the document and not just save.  You will get a sync error saying the file is in use.  These two issues are seriously making us think about going back to a server share vs using Sharepoint.  What else can we change or try?

We have all PCs updated to Windows 10 Fall creators update so we can use "Files on demand" since we do not have enough HD space to store them all.