YouTube thumbnail red stream/watched video issue

[Fred V1]

I made a huge disaster involving my now-defuct Google+ brand account and my YouTube channel and it cost me all my Watch and Search history, and comments. While I've managed to rewatch many of the old videos to restore them to my watch history and rewrote the comments that were deleted off those videos, my biggest issue is: after I watch a video on the YouTube app and didn't watch it again for 4 months, the red stream seen in the bottom of the video's thumbnail, that indicates I watched it, disappeared, despite appearing in my Watch history. My frustration grew at that regard, in my quest to restore all I've lost in YouTube. What could this mean and what will I do to resolve or compensate for it?

 

[SpookDroid]

Have you set up your account to delete your activity automatically, perhaps? Especially since Google's new push for privacy controls?

 

[Fred V1]

No, I didn't. But the video I watched on YouTube? The red stream was supposed to be there permanently, indicating I watched it. 3 months later the red stream disappeared from the thumbnail, in spite of the video still appearing in the Watch History with no harm done. Ugh, it's so frustrating, especially when I'm doing everything in my power to hold in everything in my YouTube together out of desperation. It's so tiring amd breaks my spine.