Start with the view: After slicing, open Preview. Find Color Scheme and choose Filament. Line Type uses colors to show walls, infill and other print paths. It does not show which filament makes each part.
Are the right colors now in the right places? If so, the view was the problem. If not, keep going. Save a separate copy of the project before you change settings.
These checks use Bambu Studio 2.8.2.61 labels. The official Preview source lists these views.
Check the layers where the color belongs
Use the layer slider in Preview. Look at the height where you expect the missing color. A color on the top of a model need not appear in a lower layer. Check the shape of that area too. Does it match what you want?
For example, if you expect a red base and white text on top, inspect both the base and the text layers.
Still one color? Return to Prepare and compare the same part of the model. If the color is missing there too, skip to the import check below.
Check “Flush into this object”
This setting lets the slicer use the object to clear old filament from the nozzle during a color change. Bambu warns that this will mix the object’s colors. It also says the prime tower must be on. See the official flush setting.
- In your project copy, select the object whose colors matter.
- In its settings, find Flush options. See whether Flush into this object is turned on.
- If that box is checked, clear it. Slice again and return to Preview → Color Scheme → Filament.
- Compare the same layers. Check that the colors now match the result you want.
If the box was already clear, move on. Flush into objects’ infill is a separate option; do not switch it on as part of this test.
If colors are missing in Prepare too
Check which file you opened. Keep the original painted 3MF, and compare it with the file you last saved or exported. Do not overwrite the original while you test.
Look at the project’s filament list. Check which entries the model or its parts use. Do parts that need their own colors use their own entries? Bambu Studio has a filament column in its object list; see its object-list controls.
For a file painted in Layerpaint, compare the paint in the painter with the imported model in Prepare. Layerpaint exports color data in 3MF. You still need to check which filament the slicer uses for each part. If Prepare is wrong, check the file and its color choices first. Then slice again.
If an inset part loses its color
Does your model have text or an insert that shares space with a base? This is a case of parts that share space. Bambu Studio’s overlap setting describes how smaller parts can be removed by larger ones when they share space.
Look at the parts in your saved copy. Note which one is lost after slicing. Do not change a solid part to a modifier just because its color is missing. Note the part names and layers. Ask the file’s maker to check the shape.
If none of these checks resolves it
Keep the failed example. Note your Bambu Studio version. Add the printer and nozzle preset names, and where the file came from. Take one screenshot in Prepare. Take one more in Preview with Filament selected. Show the layer where the color is missing.
Use those details when asking the model’s maker or Bambu Studio’s issue tracker for help. Share a project only if you have permission to share its contents. A useful report says what you expected, what you saw, and which single change you tried.
Before you print, check those layers again. Preview shows the planned paths. You still need to check the colors on the print itself.