Sadly, this problem has not been fixed. But As Salty says it can be "got round" by using the F12 key. First go into "Walkthrough" mode and set the throttles to the position you want them, then click on F12 and roam around the ship as you wish. You will find that the throttles stay in the position you put them at. This is something that Salty has taught me today, I didn't know this could be done.
I will attach a picture to prove the point. It is a view over the stern of "Sherpa" under full power. I would point out that I walked from the wheelhouse to the stern in order to take the picture. Normally by the time I had arrived at the stern, the ship would have come to a stop, or nearly so.
Angus.