See a specific request for isolation support in Edge at
Here are some test results that may help:
dir isolation https://www.w3.org/International/tests/repo/results/the-dir-attribute-isolation
(click on the links in the left-most column to run the tests)
Support for isolation is really a fundamental requirement for languages using Arabic and Hebrew and other scripts such as Thaana, Syriac, N'Ko, etc. Note also that the Arabic script is the second most widely used script around the world after the Latin script, so this affects a lot of people. And the lack of isolation is not an edge-case problem (see worked examples at http://w3c.github.io/i18n-drafts/articles/inline-bidi-markup/index.en#staticexamples). It's hard to understand why Edge still doesn't support isolation for any use of the dir attribute and for bdi per the HTML standard. Unfortunately, the best recommendation for users of RTL scripts around the world is currently to use another browser than Edge.
Although the W3C and the HTML spec recommend the use of markup rather than CSS for managing text direction for RTL scripts, it would also be good to support unicode-bidi: isolate.r12a shared this idea ·
See also the comments about bidi isolation in general at https://wpdev.uservoice.com/forums/257854-microsoft-edge-developer/suggestions/10784463-support-dir-auto
We’re pleased to announce that the details and summary elements are now under development :)