If data collection is working for other compute resources then there would be two things I would check
1. To make sure connectivity is good to that site (I know pretty standard but always have to check)
2. To check your DEM workers, you might have a DEM worker assigned to do data collection for certain sites so I would go to the Infrastructure/Monitoring/Distributed Execution Status and make sure all your DEM workers are online.
Those are just where I would start.