Hi Mike, do you mean aligning dynamics or grouping dynamics?
Dorico automatically groups dynamics that were input together or in sequence, but adding each dynamic separately can result in adjacent dynamics not being grouped and therefore not aligned, because the positions of dynamics are calculated (like all other notations) according to the defaults set in Engrave > Engraving Options > Dynamics with Dorico providing automatic collision avoidance on a per-group basis.
Sometimes this is desirable, as if a phrase includes some very low notes far below the staff but later notes within the staff, the dynamics at the end of the phrase can be positioned much closer to the staff than if they were aligned with the dynamics at the start, which have to be much further due to the pitches at those positions.
(Speaking personally for a moment, as I happened to have worked on parts for 2 projects in the last couple of weeks, one in either software: I spent much less time adjusting dynamics in Dorico than in Sib, in large part thanks to Dorico’s clear and pretty comprehensive default horizontal/vertical position settings for dynamics specifically. Or perhaps my Sib chops are just not quite as good!)