SharePoint Caching Problems with Lists

Hi group, I did some digging on this and believe I have found the issue for our tenant.

The OneDrive client appears to be syncing Lists from SharePoint Online (et. al) by default.  To verify this is what is happening, you can perform the following steps:

1. Open Dev Tools on Chrome (F12)
2. Navigate to "Network"
3. Select "Fetch/XHR" as type
4. Enter "RenderListDataAsStream" as a filter
5. Attempt to sort a list that is cached

The results should show "localhost", "::1", or an equivalent loopback address under the "Remote Address" column.

You can then use resmon, netstat or Get-NetTCPConnection/Get-Process to find the IM of the process name and ID of the port being used for these local XHR requests to the RenderListDataAsStream endpoint.  In my scenario, it was port 42050 (probably randomized), which was shown in use by the Microsoft.SharePoint.exe application, located under \AppData\Local\Microsoft\OneDrive\<version number>.

If you see this behavior, you can attempt to mitigate the caching by:

1. Setting 

   [HKLM\SOFTWARE\Policies\Microsoft\OneDrive] "DisableNucleusSync" = "dword:1"

   (per https://docs.microsoft.com/en-us/sharepoint/lists-sync-policies )
2. Rebooting machine, or force closing the task with IM of "Microsoft.SharePoint.exe".
3. Reloading the list page (may need to force-refresh).

This appears to be working on our test machines (all Modern UI queries are forced to use the SPO servers instead of OD), but I'm not entirely sure of the effect this setting could have in regards to SP, OneDrive, Teams, etc - so it should probably be used with caution.

Hopefully this helps your tenants as well.  Good luck!