Unable to change settings, since upgrading to 7.1.0
One thing you may want to look at is your perms.
If your Linux server uses the same group name as the username (Like CentOS), then check to make sure that your webserver can write to the applicable files in the addons directory - compare with other file perms and ownership with other modules there and then affect accordingly.
If your Linux (or BSD) server uses the user group of say, 'users' for all non-privileged users, i.e., username = jschmoe and group = users, then you may want to consider:
chown -Rv jschmoe:apache directory_name
In this case, and compare again with other files and dirs, but you may wish to:
chmod -Rv 770 directory_name # or maybe even 660
Not knowing the specifics of your install or the particular flavor of UNIX or the Linux distro you're using, I can't tell more but to suggest you check the ownership and perms comparing modules that still work with the one that no longer works.
I hope that helps!