If the powder adjacent to the block entered from the comparator, repeater or button is stretched, it will not be output to the block adjacent to the powder.
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I think is is partially covered by MCPE-11871 (which has been fixed in the 1.2.10.1 beta). However, the bottom left example in your screenshot still seems to be an issue, so we can track that one here if it hasn't been covered elsewhere.
Probably a duplicate of MCPE-14083.