Shape keys not working after editing the mesh

I have made a rigged human mesh with IK, weight paint and shape keys some weeks ago. But yesterday I changed the mesh a little bit (some proportions, e.g. made the legs longer, the arms slimmer) and than after I edited the mesh I have selected all vertices and propagated them to shape keys (vertex-> propagate to shapes), in order to apply the changes I made to the basis to all shape keys. But now the shape keys don’t work anymore. They just do not deform the mesh when they should, nothing happens. However the values at the right side of the shape keys (in the object data properties) still show up.

PS: the bones movement and the inverse kinematics still work just fine, only the shape keys don‘t work anymore.

Can someone tell me how I can solve that issue?

I’ve never really understood the point of propagate to shapes operation. It replaced all your shapekey positions with your basis positions. It didn’t add, it just straight up replaced. You probably shouldn’t have used it, because shapekeys (relative shapekeys at least) store their positions as differences from the basis, so generally speaking, changes made to your basis will automatically propagate. There are times that it won’t look good, but there’s no algorithmic solution to that, you just have to fix them.

So, revert to an earlier save.