When water is not flowing but has place to flow when piston is off it just stay that way

There is not much info about the issue, I tried to reproduce the screenshot you given and ended up is my screenshot. Does the screenshot describes your issue. If not, could you give me a proper set up or even a video for the issue. And also, expand what is the bug here?

We do not have enough information to find the cause of this issue.

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_{This issue is being temporarily resolved as Awaiting Response. Once the requested information has been delivered, the report will be reopened automatically.}

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