Are you experiencing this issue in Tableau Desktop? What happens when refreshing the data connection (right click on the data source and select "refresh") after making a change to the file? If there is an error - pleases provide a screenshot. If there is not an error - what steps did you perform to originally connect to the data from Tableau Desktop?
I work for Egnyte and also use Tableau quite regularly. I never experienced issues with it myself, but I can definitely help you find out what's happening and report it to our support, if necessary. In addition to Nathan's questions:
1) What Egnyte app are the files stored in on your desktop? Egnyte Drive? Desktop Sync?
2) Are you using a Live connection or a Data Extract in Tableau?
Regardless of the app, you do have to either refresh the data connection or reopen the workbook, because otherwise Tableau would often work out of a 'shadow copy' of the file that will not reflect any changes until you tell it otherwise. Please refer to this Tableau article for more info: Update Excel Data in a Workbook | Tableau Software
Additionally, if using Desktop Sync, make sure your files are syncing with the cloud (you have an internet connection and there are no errors in the sync).
If that doesn't help, we'll need to dig deeper. A step by step explanation of what's happening, or screenshots, would help a lot.