Marxist teachings are fundamentally incompatible with the modern left.
Let's take his response to the Gotha Program:
From each according to his ability, to each according to his needs.
UBI flies in the face of this, the welfare system flies in the face of this - yet these are two systems the left strongly supports.
Marx supported the idea that as long as you worked to the best of your ability you'd enjoy a good quality of life supported by the society you input into.
Instead we have a society where you work to the best of your ability and support those who don't, or refuse to work completely, and those who should be contributing the most, don't pay their fair share - the working class PAYE'rs are being strangled from both sides.