I’m a free user so I can not submit a proper support ticket. I seek the community’s help to confirm this bug and possibly someone can submit a proper ticket.
I have found that when caching is enabled (whether file is cached or not) .MKV streams are striped of the RANGE headers, I’m not sure where the issue is. MP4’s stream fine and range headers are all good. This issue is reproduceable by setting cache level to “STANDARD” and range headers are stripped, however setting this to “NO QUERY STRING” fixes the issue (due to all of my MKV streams containing query data). the workaround for me right now is to create a cache bypass rule
*mydomain.com/*.mkv* and the issue is now gone. However this just recently came up a few months ago… some change in CF caused this. Disable the rule, purge all cache, issue returns. enable rule issue goes away. reproduceable. if someone deals with streaming .mkv files, please add a query string (if you use it or not) and try to reproduce.
Further research seems to point to Origin server returning 206, but cloudflare returning 200 for anything with caching enabled even if not actually cached content.