Cases of Linear programming known to be in $NC$?
Fixed dimensional linear programming (for any constant dimension $d$) is known to be in $\mathsf{NC}$; in fact, it can be done work-efficiently (in the same amount of work as the fastest sequential algorithm). The more recent paper by Blelloch et al. shows that the randomized-incremental approach for constant-dimensional LP can actually be parallelized efficiently.

Alon and Meggido (1994): Parallel Linear Programming in Fixed Dimension Almost Surely in Constant Time

Blelloch et al. (2016): Parallelism in Randomized Incremental Algorithms