There is a bug relevant to the new ability to TIP Youtube channels. If you land on a channel but ‘auto-contribute’ is off, you will not have the ability to tip the channel;
You will have to close the channel, turn on auto-contribute, reload channel, tip, and then turn off auto-contribute again. After these steps it will work properly.
This can be reproduced by turning off auto contribute, open up a new tab, and going to a channel you have not visited before to try and tip.