The problem comes when you’re given a speed and a “decend to xxxx by xxx”. It can do the path or it can do the speed. If you want both you have to work at it. As someone said - moving the thrust levers manually / using the speed brake is one option.
I also find hitting the “descend now” prompt 5-10miles before calculated TOD usually results in a better flown descent as it will start down at approx 1000ft/min until it catches the profile.