Paint bucket acts "weird"

[PieterJW]

(6 hours ago)rich2005 Wrote: I do not know. I can not figure out your workflow.  There are layer effects (fx) which will affect the outcome.  Try applying the (fx) as this screenshot and then try whatever method previously used.



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For line drawing you can just use two layers, the line drawing and a transparent layer for  the fill.

Using fuzzy select tool.
Set the mode to Add (second icon)
Set Sample Merged
With a default threshold (15) enable draw mask and that adjusts as you drag the mouse in the area.

Then fill the areas with colour. Set bucket fill to  Fill whole selection.  
Important Edit -> Select None before moving on to the next areas.

If you can follow it, a quick video of that: https://sendvid.com/v9g5ym2c

Perfect! Thank you very much for your elaborate answer! Much appreciated!
I didn't know what the fx stood for and how that got there (still don't) but I clicked on the X to remove them and now the paint bucket works as expected.
Solved!

(I've been using GIMP for many years but never became an advanced user)