I have an LM-3S installed in a large scale caboose as an accessory module used to control the lighting and play some sound effects. It works great but suffers from a few controller issues.
Because it's an LM, even though it has the accessory program loaded, it shows up on the Locomotive page as well as the Accessory page. Accessing the module from the Locomotive page results in none of the accessory buttons being displayed. This in itself isn't a real problem BUT...
Once the module has been accessed from the Locomotive page or by pressing the photo on the Control Locomotive page, no matter where you access the module from, no buttons appear.
I tried lots of different things trying to fix this, including reloading the LM with both the Accessory Program and the Project file to making sure the Project file resided on the HC. None of that solved it until I tried the Clear Active Loco List function. Once cleared, if accessed via the Accessory page, everything looks and works fine.
I'm not sure if the is a "bug", and if it is I don't know if it would be in the LM or HC program. I do know that it's annoying!