What version of DevTest are you on?
You said you are using MySQL 8.0.13, we currently have only certified MySQL MySQL 5.5, 5.6, and 5.7 with DevTest, so I am not sure if this is failing due to the version of MySQL you are using.
I would also create the tables with utf8_unicode_ci and not utf8mb4_unicode_ci charset/collation. Drop the schema and create with utf8_unicode_ci.
To get additional information, add these two properties in the logging.properties file before starting the Registry (delete the registry.log file before starting to get a clean log file):
log4j.logger.com.mchange.v2.c3p0=DEBUG
log4j.logger.com.mchange.v2.resourcepool=DEBUG
Please post your results.
If still having an issue, please open a CA Support case and we can have a webex.
~~Marcy