It could be due to several reasons such as:
• Orchestrator is unavailable
• Hard disk doesn’t have enough space
• ElasticSearch Uri is not empty under RobotElasticSearch tag in web.config
You can also check if ElasticSearch Uri is empty under RobotElasticSearch tag in web.config. If it’s not empty, make it empty under RobotElasticSearch and restart the IIS of the Orchestrator. Allow 2 minutes time since there will be some delay. Then you can see the logs populating
Check out this thread
Regards
Gokul