you 're right.
4-5-1 V should work vs 3 DC but after the update in Team's set up (using boxes, remove arrows), a lot of counter formations have changed.
Now you can see 3 DC moving as winger defenders.
Positions don't matter any more.
Many times orders also don't work.
Better to be present in the game and try to "read" how it is going and do adjustments.