Hiding stems on a cue voice

[Alberto Simões]

Hello

I found this code:
  \once \override Stem #'transparent = ##t
  \once \override Stem #'length = #8

in the snippets repository, to hide a stem. But my stem continues to 
appear...

can it be because it is inside a cue voice used with \cueDuring ?

In fact, I wanted to hide all stems on that voice... (so, I would try to 
remove \once once I get it working with the first note).

Thanks :)
Alberto

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Alberto Simoes
CEHUM