So this happened to me twice recently.
One team accomplishes 1st objective on trainyard, and gets fullheld on second.
Next SW round the attacker’s accomplish the objective slower, but still win.
My theory?
If one team plants C4 before round ends (<00:50), it blows up during ‘mid-game’ menus and counts as an objective completed. Therefore, even though they have accomplished the previous objective slower, they’ve gone further in the obj completion pipeline, getting a win; when they should have gotten a loss.