Hi there,
This issue must be related to your setup as we currently have 20k+ active users and no one ever reported that the options didn’t save.
It could be caused by a plugin conflict, or maybe something related to your theme. We can look into it for you if you are interested, please reach us here: https://www.wpdarko.com/support
We’d appreciate if you could update your rating as this issue isn’t related to the plugin and it is of course possible to save your options.