Watch Later buttons not working on subscriptions page

[endymion0000]

For the last few days, my watch later buttons are not working anymore when clicked on the subscriptions page. When I click them I get a red square with a X and the tooltip says undefined. I'm using Safari 8 and the latest developer version using the Javascript Blocker extension. Works correctly with YTC disabled.

Console shows the following when a watch later button is clicked.
[Error] Failed to load resource: the server responded with a status of 400 (Bad Request) (playlist_video_ajax, line 0)

Not sure if it's related or if all of this is due to YT changing their stuff again...

In the same time frame I've also had video pages just not load the video and the YTC settings icon is no longer up in the corner at that time, but still appears on other non-video youtube pages. Reloading the pages doesn't fix, but sometimes turning off the javascript blocker extension to disable YTC, reloading the page which loads like YT normally does, then re-enabling the extension and then reloading and it sometimes works again.

[endymion0000]

Hmm, this may be due to the AdBlock extension since there's a similar thread mentioning it as a problem.

[YePpHa]

@endymion0000 I would guess you're right it could be an issue with AdBlock as YouTube Center does not tamper with your connection at all and could therefore not be the cause of the error you mentioned.

I will close this issue because it's most likely not the cause of YTC.