Hello,
Thanks for reporting, I have not encountered this issue before.
So you say that the button does exist, but it is not clickable?
I know you say you checked the log, but I am guessing that a PHP error might be breaking the rendering of the admin page. Normally at the bottom of each admin page for the plugin, there is a message “Found Bitcoin and Altcoin Wallets useful? Want to help the project? Please leave a ★★★★★ rating on WordPress.org!”.
1. Do you see this message on the coin adapters page?
2. Are you on a multisite install?
3. What happens if you deactivate other plugins?
Please let me know.
Lastly, if you wish me to login and check it out, you can email me some credentials and I will have a look.