eNewsletter 2.7.1.8 broke Wordpress

Hi,

I just updated eNewsletter to 2.7.1.8 and I can no longer edit newsletters. Whenever I try to edit a newsletter I am redirected to the themes page.

This is what I have tried:

1. Disabling all other plugins.
2. Changing back to default theme from Avada.
3. De-activating/ re-activating eNewsletter.

Any ideas on what else could be wrong?