Lava filter doesn't work with non-square selection on separate layer
OS: Windows 10 Home, 64-bit.
GIMP version: 2.10. 34, 2.99.16, and current master.
The lava filter see incomplete documentation doesn't work correctly when
- Keep selection and separate layer are both checked; and
- The selection is not square, but e.g. oval.
With an oval selection, it seems that it changes the output lava to a square that fits the oval. The selection is also gone after that. If instead you only checked keep selection without separate layer, then the correct oval is filled with lava, and the selection is still there.
Another more random selection changed the lava to fill the entire layer.