Created attachment 348840 [details] Laptop Screen shot with correct rendering This can be seen when running on an iPhone compared to a browser running an another rendering engine. I keep seeing the problem on the iphone when referencing websites with Hebrew vowel markings. I'm surprised I couldn't find this issue at Bugzilla. Here is a unicode HTML that I ran as a test: http://www.newelsys.com/Test/Hebrew_Niqqud_Trope.html Attached is the screen shot showing the correct rendering on my laptop using Chrome.
Created attachment 348841 [details] iPhone rendering of Hebrew text, the markings are missing.
Have you tried the latest iOS 12 betas? I can reproduce the bug in 11.3, but see the vowel markings myself on the iOS 12 beta.
I just ran the test on iOS 12 Beta Public 10 release. All markings are correct.