XeTeX Redux
Published at 23:22 on 27 October 2023
It is a known bug. The workaround is to use fontspec to invoke the feature manually, e.g.:
\fontspec{Baskerville}[Renderer=OpenType, RawFeature={+smcp;-liga}]
Ligature substitution should be disabled when using small caps because the two features tend to be incompatible.