This is an error that took us an hour to figure out.
We are using the right-arrow icon as part of the content within a collapsible header to represent a transition. (See image)
We found that the expand/collapse icon did not appear.
Further investigation reveals that if the header content contains a span with a class matching the regular expression k-i-arrow.* then the expand/collapse icon doesn't work.
See this example. https://dojo.telerik.com/EwAsaKAf/3