This bug in the attached forum post has returned. To summarize, cylindrical boost volumes do not work in Ball Race maps for players who are not the host.
Steps to Reproduce
Host a custom ball race map that has a cylinder boost volume (for example, Downtown) and have another player join. When you get to a level that is supposed to pull you upwards through a tube, players who are not the host will find that they are unable to be pulled.
What I expected to happen
The cylinder boost volume to pull all players.
What happened
The cylinder boost volume pulled only the host.