The default timeout for the REST API call to retrieve the list of gateways is set to 20 seconds. In some cases, due to the metadata, the API call does not receive a response within this time frame and subsequently times out. As a result, the front end shows a "No data" message.
Increase the timeout setting for the Library to a higher value, such as 120 seconds.
Add the parameter to configOverride.properties (WEB-INF/classes/config/configOverride.properties):
http.requestTimeout = 120000
Restart the Library server for the changes to take effect.