When oploading a .obj file, invisible texture parts turn black

See https://mcreator.net/wiki/custom-obj-models-blocks-and-items

Put the objects transparancy type to either cutout or cutout_mipped in MCreator

I can't find anything there

From the page linked above:

Material Limitations

Only very basic materials are supported. Only basic transparency is supported for the time of writing. It is said that this support is to be improved in the future, but this depends on when Minecraft adds support for this as we use their model loader. Advanced shading will be reduced to basic shading and all advanced material settings like metalness or roughness will be ignored.