Created attachment 310642 [details] Screenshot of Safari and Chrome (for comparison) In the following example, all characters should be rendered sideways because all of them have "R" property of UTR#50. https://jsbin.com/hohaxuqece/1/edit?html,css,output However, the numbers (123) in the second line are rendered upright on Safari. The problem occurs with Source Han Serif, but does not occur with Source Han Sans. I found that the issue won't occur without "latin_special" lookup substitutions defined by: https://github.com/adobe-fonts/source-han-serif/blob/master/Regular/features.JP#L2755
<rdar://problem/32319157>
It looks like this is fixed now. Can you check again?
Safari 11.1.2 (13605.3.8) looks good. Thanks.
This should now be fixed in shipping software.