I forgot to report this, but all our programs are obsfucated. Therefore when we call update manager, there is always new releases to apply because assembly version to shimmer is reported as 0.0.0 when it's actually, i.e 1.2.3102.
The problem can easily be solved by adding a parameter overload accepting a "here is my real assembly version" version :)
Today we solve it by manually resolving the update graph ourselfs by excluding any prior versions to currentVersion