The name does not refer to any table in Log Analytics

Solution 1:

As per the MSFT documentation, it takes up to an hour to display the initial data from a new custom log in Azure Monitor. It will start collecting entries from the logs found in the path you provided, once you define the custom log. The entries that you uploaded during the custom log creation process will be not retained, but it will collect existing entries in the log files it locates.
Please refer this documentation - https://docs.microsoft.com/en-us/azure/azure-monitor/agents/data-sources-custom-logs#step-5-validate-that-the-custom-logs-are-being-collected