I think LENZ has a programming track. Make sure you are programming each Lok on the programming track.
We used to do programming on the main with our club layout. Then one user accidently did program on the main in Blast mode. ALL Loks on the layout at the time were programmed the same address. Took some time to clean up!
We now have a separate programming station. Separate table. NO connection to the layout.
And there are programming features you need to be aware of when programming. Most new sound decoders are using 'indexed' cvs to manage the thousands of CVs. You need something like JMRI (or Lokprogrammer) to be sure you are programming the feature you expect, not some random wrong CV. (Set CV31, set CV32, then read/write CV2xx)
It does make a difference what decoder brand and make you are programming. Please include that information.
And like Alan said in his post, turn off DC detection in CV29. WE had that issue too, Loks would start, stop, start, stop,.... the DCC system would confuse some decoders, and those loks were flipping between DC and DCC running.