Seems to work with an expression. I record off-site, and transfer the file via OneDrive overnight, so I put the expression in auto import, and it works great. On my off-site recording machine, I will put it in the subscription rule (modified since I won't need to use the IfElse portion). Here is the expression:
IfElse(isequal([Series], Magnum P.I., 1), 350068, isequal([Series], MacGyver, 1), 311902, isequal([Series], The Profit, 1), 271671, isequal([Series], The Goldbergs, 1), 269653, isequal([Series], The Flash, 1), 279121)
I will add series to the expression as needed, but so far, the background images have all been correct.