It’s not you. It’s Bases.
Seems related: In .base files, local URIs in formulas do not open
Back then, however, the formula versions worked when the base was embedded (code block or link embed) but didn’t work directly in the .base file. A few people confirmed, and the team repro-ed.
But testing anew in the latest release, I think the formula versions work in neither context. That is, it no longer works in embedded contexts.