It is not possible at this time to separately exclude folders or files outside the standard time based policy. One potential option is to make this directory a junction link and cloud tiering will skip it. You can review what is excluded and skipped here. So you can setup a separate folder that sync doesn't touch and make a junction link in the place where it currently is that points to the other folder. This page walks you through how to setup a junction link
Hope this helps! Let us know if you have further questions or issues and we will do our best to assist.
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