I created a London Underground livery for the Class 483/38 Stock, and it's not appearing under "Reskins" in the Scenario Planner. Edit: I've tried it with the 72 Stock as well and my created liveries aren't showing up. Edit #2: It's not even available in Timetable Mode...
I reported the thread, and in the report, I asked for it to be moved. Unfortunately, my patience is too low and I already created a new thread about this in Tech Reports.