Custom Classification Not Assigning - Unable to verify Classification Rule - System Error

Hello, I am experiencing an issue when trying to scan and apply custome classifications. I am the Collection Admin (and inherited for Data Source Admin and Data Curator). I am using the new Purview portal.

I am able to create the Classifications, the Classification Rules and when I run the scans none of my (15) custome classifications get assigned. The rule is basic to locate a series of 'INV001' for Invoice, 'OWN001' for Owner, etc. I create the classification Data Pattern via uploading a sample file to get the Purview recommended pattern (^[0-9]+[a-zA-Z]$). But when I run the scan I get zero custom matches for my files. 
When I go back into the Classification Rule and run a Test Classification Rule, I upload a sample file of the simple rules i am trying to validate (INV001 or OWN001 etc. ) - using the same file that proposed the pattern, I get an error 'A system error occurred. Unable to verify classification rule'. 

I have seen the requirements to be the following:

• Check if you have the correct permissions to apply custom classifications and classification rules. You need to have data curator or data source administrator permissions on any collection to be able to create a custom classification. //YES, I have these roles.//
• Check if the scan rule set is configured correctly. The scan rule set determines which classifications will be compared and applied to your data. For more information, see how Microsoft Purview classifies assets in the provided document.//Yes, this is the file used to create the pattern in the rule//
• Check if there are any issues with the data source itself. You can try rescanning the data source and see if the issue persists.//The files tested are simple 10 row files created for this purpose//

I have retried several times and keep getting zero custom classifications applied. Any guidance from successful custom classifications in the new portal is appreciated.