I have sound dropping out on my Atlas Double Switches too. My Vision Line GG1s both loose sound. I sent my ATSF 4-8-4 back to Lionel when the factory forgot to put battery cables on it. The factory was able to add the battery cable.
If the new engines don't have battery cables, I am done buying engines. My Atlas 90-degree double cross overs also require batteries to make it across two cross-overs.
Sincerely, John Rowlen