When I had the problem, I tried to contact Kobo consumer's service
. I was redirected to FNAC as in France, they distribute the Touch. I got an answer just today (fast answerers aren't they ?
) to tell me that with the new firmware, having the cover on display during sleep or off time was just not more available (as it's explained how to do it in the "help menu"). And they go content with that
Shame on you FNAC