Just my two euros worth.
You can check, but the palette something.gpl is not written to file, until Gimp is closed.
I do not have a MacOS (of any version - my VM no longer works) but I do recall that not all folders were created on installation. Do you have an actual palettes folder in your Gimp user profile. /Users/{your_id}/Library/GIMP/2.10/palettes ?
Next question if the folder exists, is it writable ?
Quote:I close the Palette Editor and verify that the new palette is still listed. I double-click on the palette’s name in the list on the Palettes tab to open it again in the Palette Editor, and I verify that it contains the colors that I added to it. I close it again. So far, so good, but after I quit Gimp and come back some time later, the new palette is gone.
You can check, but the palette something.gpl is not written to file, until Gimp is closed.
I do not have a MacOS (of any version - my VM no longer works) but I do recall that not all folders were created on installation. Do you have an actual palettes folder in your Gimp user profile. /Users/{your_id}/Library/GIMP/2.10/palettes ?
Next question if the folder exists, is it writable ?