An EMS provider may have their license revoked for all of the following EXCEPT:

The correct option highlights that an EMS provider may not have their license revoked solely for having an outstanding fee. While it is critical for providers to maintain good standing, including paying any fees associated with their license, an outstanding fee alone does not lead to license revocation.

In contrast, operating a service while the provider license is under probation can lead to more severe consequences as it indicates that there have been prior issues with compliance or behavior. Similarly, operating while appealing an administrative action may also risk revocation because the appeal process itself does not absolve them of current licensing conditions. Finally, operating with a suspended license presents a clear violation of regulations that directly endangers the legitimacy of the service and can lead to revocation. Hence, while all the other options involve situations where the provider's adherence to legal and professional standards is compromised, having an outstanding fee, in isolation, does not inherently compromise the legal status of the license to the same extent.