Admin settings bugs after update to 4.0.3

After an update to 4.0.3 on my development site, I am experiencing issues in the following admin settings sections:

1. Thank you templates: no changes take across subsections. Blue button below test email address is a “Save Changes” button, so whenever I attempt making a modifications to the Email Template settings below, I receive the “* Valid email address required” validation message. After hard refresh of page, any changes made reverted to their original values.
2. Settings:

• Notification Emails: can edit, but if entering multiple values separated by comma, the comma is stripped out after save attempt
• Paypal Settings: no changes take

I’ve disabled all other plugins and am running the twentyfifteen theme. Log: http://dev1.rfros.com/?attachment_id=1494; email attempt before: http://dev1.rfros.com/?attachment_id=1492; email attempt after: http://dev1.rfros.com/?attachment_id=1493

https://wordpress.org/plugins/seamless-donations/