When re logging into a world you previously saved with redstone sometimes in a rare case the button or lever powering it would not work and you have to place a new one.
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bemoty
Thank you for your report!
However, this issue is a Duplicate of MCPE-17304.
If you have additional information, please add it to that report.
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I happened to me once too i didn't know what happened but the lever will flip but not a single redstone will power. It only happened to me once so it is very rare