nisystemlinkforwarding.exe will continually log this error as long as it has APM data that it wants to forward, but cannot.
The forwarding service is trying to publish Asset Utilization data to the server, but it is unable to see the APM service. This isn't really an "error" for the forwarding service, more a warning, as it will retry until the APM service becomes available.
All the Asset Utilization information from all sources goes through that forwarding service. Even if Asset Utilization Tracking is disabled in TestStand, there could be something else on the system publishing utilization data.
This error message will continue warning until it manages to successfully publish all the leftover utilization data on the system. Even if the source creating the data is stopped, the previously created utilisation data will still be there on the target, waiting to be synchronised with the server.