Hi Wouter
It\'s a bug, We are working on it.
The workaround I can suggest for now is to copy Typemock extension folder
and paste it after silent installation manually.
It is located in C:\\Program Files (x86)\\Microsoft Visual Studio\\2017\\Professional\\Common7\\IDE\\Extensions\\Typemock\\Typemock Extension\\8.7
I will update you once it is solved.
Cheers,