View not rendered properly when HTML 5.0 Syntax is disabled.

I'm sorry but I need more details for fixing this. I just started a fresh version of xwiki:17.4-postgres-tomcat, installed Change Request 1.19 in it, checked that the disabled syntax is set as you mentioned in the description (default settings), enabled the rendered diff view in change request and then performed changes, and I've no issue to get the rendered diff.

So maybe you have some other specific setup or administration settings? Any proxy in front of your wiki? Did you experience issues when performing editions on standard pages outside of Change Request: note that CR uses the standard mechanism we use everywhere else to render XWiki syntax to HTML and then parse it again.