thank you for your post! actually this is a bug, which will be fixed in the next release version (past 18.104.22.168).
Within the monhtly balance calculation, the effective heat recovery efficiency is calculated, depending on the ventilation device HRV/ERV efficiency and e.g. the ducts.
by assign the boundary condtions from passive house model, the effective heat recovery efficiency is set for the HRV/ERV efficiency of the device, for the dynamic simulation (because there is no dynamic duct model so far).
unfortunately it replaces also the input for the verification side. So with each click on assign, the HRV/ERV efficiency for the mechanical ventilation device is reduced.
I will post the insight on what is being changed soon, and it will be added in the manual. The data update with the prepopulate boundary condition button should be one-way (from verification to the dynamic inputs) and only for dynamic WUFI Plus input, which is not used, or different on the verification side. global input, like the building geometry, is always coupled in both scopes.