Import FBX back to Mixamo after correcting bone weights in Blender

I'm trying to prepare a "read-to-use" human character with rig, so that I can import it into Mixamo and download the animations I need at any time.

I tried and I realized that when I upload my model to Mixamo, and then download it as an FBX an reupload it to Mixamo, it reads the armature perfectly and I can simply choose a different animation to download.

The thing is that I would like to correct the bone weights in Blender (because the automatic weight from mixamo are really good but not perfect) and THEN use the corrected rig to download new animations. But every time I try to reupload to Mixamo after exporting from Blender, it is unable to read the armature and it asks me to assing the bones again, which makes correcting the rig useless...

Is there a way to make it work? Could it be fixed by changing Blender's export options? The only thing I touch in Blender is the weights, I don't change anything else.