I think it’s true that the scientific evidence is not strong. Serifs and font legibility found “When text is small or distant, serifs may, then, produce a tiny legibility increase due to the concomitant increase in spacing. However, our data exhibited no difference in legibility between typefaces that differ only in the presence or absence of serifs.” The study used both computer monitors and paper.
In A matter of font type: The effect of serifs on the evaluation of scientific abstracts, “The results show that missing serifs led to increased reading speed. However, and in contrast to the perceptual fluency hypothesis, the presence of serifs had a positive effect on all evaluation dimensions. The results of a second study with 187 participants also indicated that reading fluency counteracted the liking of texts.” These studies were done online so text on screens, not in print.
Those are just a couple which can lead many more with varying results.