Hi. The paint bucket seems to be almost a deprecated tool, nowadays. Please see if this happens if you have your selection, then use Edit>Fill>and choose Foreground color. On a high resolution image, your bucket may be trying to see if there are many/a lot of edges to detect. Edit>Fill is more direct. If it works, you can always fill a selection with the foreground color by typing Opt/Alt +Delete/Backspace
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