Problems after WordPress 4.5 update

After the WordPress update 4.5 has been updated, I am facing two problems as follow:

– The media uploader button does not work anymore: pictures need to copied and pasted one by one from the directory to the new post’s text, what takes time, besides needing to be saved as draft each time a new photo is pasted

Last but not least

– subscribers’ email notifications have stopped when new posts are published:
the newsletter plugin installed is mailchimp 1.4.5 . It means that subscribers don’t know that a new post is published, decreasing dramatically the number of visitors

Please, I urge to solve the last problem as soon as I can.

Thanks in advance