Hello!
Thanks for this information. Really helpful. It's important here to understand one concept: Base license and Attach license. A base license is normally the first license you purchase. IT will provide you some storage, access to the applications. On your particular scenario, the base license was the Sales Professional license.
The second thing is, an Attach license. It means that for a user that has already some access, you need to provide a different set of funcionalities. For example, Sales Managers that have a Sales license, could get an Attach license in order to use Customer Service to generate cases on behalf of their customers. Another example: Users with Field Service license getting a Sales license in order to make in-place associated sales. get access to product catalogs, generate opportunities/leads while working on a particular order.
And here lies your problem: Licensing guide has a nice table:
If you take a closer look, users with Sales Pro can NOT have Sales Enterprise. You have on your subscription an Attach license but not a base one. In order to fix this, you should purchase a Dynamics 365 Sales Enterprise license and cancel the current Attach one. The other possibility is if your user has some other license (for example, a Finance licens) in which case you could assign the Sales Attach.
Regards,
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