According to this question:
Marx did not need to invert historical idealism because Schelling had already shown the limitations of the dialectic process
Hegels dialectic, roughly, is manifested in how Spirit manifests itself in the world, starting from Nothing & Being synthesised to Becoming.
Whereas Marx historical materialism inverts Hegel by showing how the World manifests itself in Spirit through economics.
How does Schelling, before Marx, show that Hegels dialectic has its limitation?
Further, I find it thought-provoking that one could take Hegels dialectic as a thesis and Marxs as an anti-thesis, with a synthesis perhaps not yet making an appearance, or perhaps as Post-Modernism which disavows grand narratives (both of which Hegels and Marx systems are) and champions eclecticism and multiplicity as opposed to the universal-systemising and thus univocacity of Marx & Hegel. Is there any substance to this?