Hi Greyfox,
I've been reluctant to add to your confusion but your question has simple answers that have already been provided. I'm not being snarky here but suggest you carefully read a primer on DCC and how it is different from analog control. It can be confusing when you first begin using DCC. If you don't understand the differences between analog and digital control and mix the two incorrectly things wont work and there is a strong possibility you'll see smoke too!
Also, you were asked to provide a diagram of how you have your Massoth and LGB components wired together. You may think your verbal description is sufficient but there is a reason for the adage "a picture is worth a thousand words." Please draw a simple diagram showing what is connected where with the connections labelled, take a picture of the drawing, then attach the picture to your next post. Don't forget to include where the EPL switch drives are connected in your diagram. It will be very useful to those attempting to help you. In fact, with this exercise you might just realize where the problem is on your own!