checkupdates does not work with temp repository

I add a temporary repository and want to check for updates:

MaintenanceTool.exe --setTempRepository http://196.120.40.1/repository_x64 --checkupdates

I always get back: There are currently no updates available.
Although there is a new version available.

When I just start the MaintenanceTool without the check:

MaintenanceTool.exe --setTempRepository http://196.120.40.1/repository_x64

I can perform an update.
So the update check does not work.