What I understand is, the modifier {Team]={'Original'} overrides the selections in the Team field. So whatever you choose, this particular chart would not be affected by the selections in Team field. the {$<>} allows to make selections in other fields and they will impact the result.

I think you need something like this, need to test the syntax -

Sum({$(<[Team] = {'Original'}>*<Team=P(Team)>)*<Month = {"$(=Month($(vMaxDate)))"}>}[Lead Goal])