To help with this I think I'd need more information about your source data, namely the structure. The easiest way to demonstrate this, as well as the issue you're experiencing, is by attaching a .twbx which mimics your setup. You can attach a file in the advanced editor (link in top right corner of the reply box).
Thanks for the reply. The file is too large to attach a .twbx file and for confidential reasons I would prefer not to attach it. I was hoping that someone might have some reasons why this might be happening
Hi Eric and welcome to the Forums!
You can copy a small subset of records, retaining your original data source's structure, into Excel, and randomize/blind as needed, then simply copy and paste back into Tableau as a new data source in place of the original, and use for demonstration purposes (set up the TWBX as close to your production workbook as possible so we can see your work and hopefully what went wrong). This will take a little bit of effort, but you'll likely have an answer to your problem by the end of the day if you can do this. Otherwise, there's really no way for us to know what is happening based on your original question--we'd at least need to see some sample records in the underlying data.
If that won't work for you, you can mock up a similar example using dimensions in the Superstore Sales dataset included with Tableau. Either way, posting a packaged workbook will be the best way for you to get the help you needed, as Noah mentioned.
For more information on why we ask for this, a user created this helpful doc:
Matthew... is that link right?
Nope, fixed - thank you!