Hello,
I am sorry that you are running into this issue. Due to changes in the version 6.3 API, the Kaseya plug-in only supports ERA v6.2. We are in the process now of fixing these issues and an updated version of the plug-in that supports ERA 6.3 will be available near the end of March/beginning of April.
In the meantime, to fix the activation task issue you can perform a query on your Kaseya database that will prevent these empty tasks from getting created. "UPDATE eset.ClientMetaData SET pending_operation = 0"
I hope that helps!