Why aren't my players staying on my Taxi Squad?

If the commissioner adds the Taxi Squad positions after the start of the season, and some owners have already set up future lineups, then they will need to update each of those future lineups with their Taxi Squad updates. (We wouldn't want the system to override anything that was previously customized in regards to the lineup.) When the owners get through all of the future lineups that were set, this will no longer be an issue.