I was recently watching a stream. I'm on 74 streak and it was supposed to increase to 75. I watched only the one stream, got points, tried different browsers and even the app.

It didn't update whatsoever. The streak stayed the same, it didn't reset (yet) nor did it increase. I've seen other people addressing the same issue.
I contacted twitch support, but they just told me to come here without addressing my issue or offering me help in knowing what is going on with my streak.

There should be a manual check in which could be used once per stream, not this system which tells you if you have a streak or not. The users themselves should be able to claim the streak. The automated system is buggy and inconsistent. Current system can be kept, but an alternative option should be added.