Mixing numbers and uppercase letters in Libertine

I'm writing a document that uses ACM's acmart document class. I have no way of changing the class itself or its font definitions.

I have some words that contain a mixture of numbers and (uppercase) letters, and they come out in SpONgeBoB CaSE:

\documentclass[acmsmall]{acmart}\begin{document}Xilinx \liningnums{XC7A50T}\end{document}

I thought this is what \liningnums is for, but alas it doesn't seem to change anything (I guess it's already using lining numbers by default).

Is there a way to align numbers and uppercase letters better with Libertine?