I have a rigged human character with many corrective blend shapes, which sometimes overwrite each other. For example, the corrective blend shape on the finger, when activated, “un-does” the corrective blend shape on the elbow, when both the finger and the elbow are bent.

I have tried the input editor, and can change which blend shapes overwrite what other blend shapes, but they still overwrite each other.

My next step is to try and paint the areas which the blend shape affects (stop the finger blend shape from being applied to the elbow). However, when accessing the “Paint Blend Shape Weights” tool, most of the target blends do not appear in the list. Two target blends do appear, but the two which appear are seemingly random and have nothing that sets them apart from the other blend shapes which do not appear.

When creating new blend shapes from the same base mesh, the new blend shapes also do not not appear in the target blend list.

When attempting to duplicate the problem (with several cubes), the issue is not present.

Does anyone have any ideas on how to prevent the blend shapes from overwriting each other, or how to fix the issue with the targets not appearing in the paint blend shape weights list? Attached is a screen grab of some of my blend shapes visible in the blend shape editor on the right, and them not being present in the paint blend shapes weights list on the left.

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off the topic question when paint weights did u use the mirror weight tool.im currently painting weights and the tool refuses to work correctly for mr

In case anyone stumbles across this post with the same issue I had, I finally found the fix to this bug -

The workaround for this is to right click on your base mesh, and while holding down right click, move down to paint > blend shapes > and then select your blend shape from the pop out menu - they’ll all be there, even if they aren’t visible in the normal tool options for paint blend shape weights.

Hope it works for anyone else having this problem!