The credit for this goes to Phil Klopp, with whom I just got off the phone.
The bug under discussion is defined as follows:
- A PS2 or PS3 engine is associated with a TIU the last time it is either added or when a READ is performed.
- The engine may only be associated with only one TIU at a time and it is always the last one to which it was associated.
- An engine in a DCS remote's Inactive Engine List cannot be made Active because the engine is sitting on a track belonging to a TIU other than the one with which it was last associated.
The solution to this problem has always been to either issue a READ to re-associate the engine to the TIU whose tracks it resides upon or to physically move the engine to a different track that is connercted to the TIU with which the engine is currently associated.
The former solution may be unpleasant because it will send all unpowered PS2 and PS3 engines, as well as all TMCC and Legacy engines, to the remote's Inactive Engine List, possibly making things worse instead of better.
The latter solution may be very inconvenient, particularly with multi-unit engines or large steamers.
I'm happy to say that Phil Klopp has found another way that is simple and elegant. When attempting to select a powered-up PS2 or PS3 engine that should come out of the Inactive Engine List but instead displays an error message, as soon as the error message goes away and you see the engine list, simply power off the DCS Remote and power it back on. The engine you were attempting to make active should be the active engine in the remote's screen. Press Startup and it should come up and run.
Again, many thanks to Phil Klopp for calling this to my attention! 
