Solver Yossi Fendel alerted me to a bone-headed mistake I made while constructing this week's puzzle, which renders the meta unsolvable! (Though Yossi impressively managed to figure out the solution I was going for anyway.) So if the meta has you stumped, it's not your fault.
I'll explain the intended answer next Monday, but in the meantime you can either just treat the puzzle as a themeless, or try to figure out the meta anyway. If you do, you'll have to switch two directions in order to correct for my mistake.
A thousand apologies! I'll post another meta next week, this time one that actually works, to make up for it.