Four-dimensional quadratic forms over $\mathbb{C}(\text{\hspace{0.17em}⁣}(t)\text{\hspace{0.17em}⁣})(X)$

For quadratic forms in $4$ variables defined over the rational function field in one variable over $\mathbb{C}(\text{\hspace{0.17em}⁣}(t)\text{\hspace{0.17em}⁣})$, the validity of the local-global principle for isotropy with respect to different sets of discrete valuations is examined.