A potential compatibility issues was brought to my attention. The issue was caused by me using the default names of SCS trailers in the latest addition rather than giving them new unique names as I normally do. If you happen to be using another mod with the same cargo it would cause trailers not to appear in game.
This issue has been fixed and version 6.4.3 is now available to download.
In other news, I have spent most of the past week playing with a Kenworth K200 in ATS.