Thread:Extension talk:WYSIWYG/IE11 with MW 1.22.0 + WYSIWYG extension: Existing category definitions will corrupt after after page has been saved

IE11 problems:

Creating first initial category definition works on page where there are no categories before. After editing page with IE11 where there already is category defined, category definition will be corrupted after page has been saved.

It will be also corrupted if button "code" is pressed (to toggle between wikitext and wysiwyg view). I quess this is same kind of issue as in post by "Hoggle42 (talk)‎19:20, 20 November 2013" https://www.mediawiki.org/wiki/Extension_talk:WYSIWYG#Editor_removes_assigned_category_16286

Any ideas why this happens only with IE11? (..it works ok with Chrome and Firefox)