Actually, scratch all of that.
Steinberg’s first law - Daniel is always right (and I’m wrong).
jamwerks, the accent in the top piano stave in bar 4 already has a negative offset - you’ve asked it to go lower.
It can’t go lower because there’s a slur and you have the following Engraving Option set:
This is a bit complicated to explain, but I’ll try.
I believe that what’s happening is this:
When you drag an accent with the mouse, Dorico measures the distance you actually drag. The following distance is about 4 spaces.
The natural position (no Y offset) of the accent is here:
Dorico’s already added an offset of about +2.25 spaces to get the accent above the slur (as the Engraving Option dictates). At some point you’ve knocked the offset down to -2.875, but Dorico’s leaving the accent above the slur. If you drag the accent +4 spaces, Dorico doesn’t calculate the move as (current automated offset) 2.25 + (drag) 4 = 6.25 spaces, it calculates it as (existing offset) -2.875 + (drag) 4 = 1.125, which is lower than the 2.25 offset that’s the minimum that Dorico can get away with (because of the slur).
Capiche? (I won’t be offended if the answer’s “no”!)