Most people who have looked at it say x-ray emission losses would prevent achieving breakeven. I am not equipped to evaluate the assertion, but private investors have favored other designs.

There is a split between thermal-equilibrium designs, like Tokamak, and those relying on non-linear plasma fluid effects to achieve much greater compression in selected places and/or times where fusion should happen. Plasma fluid dynamics is tricky. Plasma fluid radiology is harder.