I double checked the source code the BingMapsRESTToolkit and it is correctly setting Minute as the time unit on the distance matrix request. The response is parsed as-is returned from the service. As a test, you can check the POST body being created for your request using the GetPostRequestBody method. In there you should see timeUnit: 'minute'
Can you provide a sample of the POST body where you are seeing the issue. Then we can try calling the service directly and seeing if its an issue with the response from the service.
Update
The Bing Maps Distance Matric API does not support truck, so the BingMapsRESTToolkit tries to workaround this by leveraging the truck routing service using this code: https://github.com/microsoft/BingMapsRESTToolkit/blob/master/Source/Internal/TruckDistanceMatrixGenerator.cs Digging through the code it looks like for the first cell it accidentally multiplies by 60 rather than dividing in this line of code: https://github.com/microsoft/BingMapsRESTToolkit/blob/3a18ed3d5c4ab9516423ec54ad9f2658dfce5eff/Source/Internal/TruckDistanceMatrixGenerator.cs#L113 All other cells look to be converted correctly. I made a pull request on the project to fix this issue, however I'm not sure when the NuGet package will be updated again (last updated in 2018). With this in mind, you might want to just divide the first cell by 3600 (divide by 60 to get back to seconds, then divide by 60 to get to minutes).