Unwanted color lines in multicolor print

[noswall]

I have a simple model made up of a triangular base piece and letters on each side. I want the letters to be different colors, so I imported my model and used the fill option in color painting. Depending on the layer height, I am getting unwanted lines going through some of the letters. For example, in the attached screenshot, there are two blue perimeters that should not be there. If I increase the layer height, this goes away.

Bambu Studio seems to know that the letters are separate objects, as the yellow goes back into the main body. What could be causing these rogue lines? I have wipe into infill turned off.

[Christian]

Are the letters fully colored at the preparation-view? Sometimes there are small lines that arer not fully colored. If the slicer hits these lines, you see them in the wrorng color.

[noswall]

Everything looked nice and clean in the preview. I went back and changed the color of each object, instead of using the bucket tool. That seems to have fixed it: no more random lines of the wrong color.