With MailChimp Add-on active can't assign a membership to a member

1) When MailChimp addon is active, it is impossible to assign a membership to a member manually. The fix suggested in this thread is not working:

2) The options do not remain saved in Membership 2 > Add-ons > BuddyPress Integration add-on. Currently, the "Use BuddyPress Registration" option is deactivated after some time it is enabled by itself.