Unsubscribe from video/image preview is not working.

Summary

(Summarize the bug encountered concisely)

Steps to reproduce

1. Go to a subscribed user.
2. Scroll down and select a media.
3. Press the down arrow in menu below media.
4. Select unsubscribe.
5. Navigate to user profile again.

Platform information

HUAWEI (HUAWEI ANE-LX1) / Android 8.0.0

Environment: Huawei P20 lite, Android 8, Chrome browser

What is the current bug behavior?

Content author is still subscribed.

What is the expected correct behavior?

Content author should be unsubscribed.

Relevant logs and/or screenshots

https://dashboard.ubertesters.com/uploads/8463/11810/issues/15/151650/unsubscribe%20is%20not%20working.mp4

Possible fixes

(If you can, link to the line of code that might be responsible for the problem)