:root not being picked up on templates

This was an issue that we had some time ago. My spacing and sizing are all variables pulling from a stylesheet. Regular units are fine, but backend not displaying any of these values.

Screenshot of backend:

Template Editor

Same blocks copied into a page

A post on the front-end:

Was a problem on the previous version. Persists with the 1.2.9.4 and 1.2.9.4.1 updates earlier today.