Pistons and other redstone components does not get powered diagonally anymore. I hope this will get fixed very soon.
Linked issues
duplicates 1
Comments 2
Thank you for your report!
However, this issue is a Duplicate of MCPE-14664.
That ticket has already been resolved, which means this is not considered a bug and won't be fixed. Please do not leave a comment on the linked ticket.
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Bedrock does not have Quasi Connectivity. That is a Java exclusive functionality that will not be part of the Bedrock redstone setup.