Projects Failing due to Analyses Suspended (Missing license)

Since the upgrade to v6.7.4 (from v6.7.1), all analyses fail with the error message:
“Analyses suspended. Please set a valid license for the commercial features you installed.”

After reading through stackoverflow comments, I discovered the SonarSwift and License plugins had been installed but were not supported, so I have removed both of these and restarted Sonar, but still the error persists.

Is there something else I need to do to refresh this check or release this error/flag ?

Thanks.

**** Update 06/20 19:09
This problem was resolved today. I cannot explain the solution; but projects started running successfully again after logging was changed to “Debug” levels, and the system was started again.
Please delete post if required. Thanks.