Hello,
At this moment you are using the old version of theme 4.26 and I would not recommend you to use auto update to update theme to version 5.1.1. 5.0 update – was major theme update and it would be better to update theme manually. Please, provide me FTP access to your site to help you with theme update to 5.x version. Also, check the updated demo http://xstore.8theme.com , we made a lot of changes in 5.x version including style changes https://xstore.8theme.com/update-history/ , make sure that this is ok for you.
Regards