Image as a grid cover

Hello, how are you?
I hope you can help me.
I’ve been having problems with my site, I’ve already done some procedures with my server, changing settings through dreamhost and also settings related to worpress, and I’m considering it to be a problem with the theme.
The site became very slow, in addition to the functionality of changing the page between the Portuguese and English sites being sporadically failing, recently the site started to have problems with the display of images on the grid, now not even the option to configure the image in these criteria is available.
We have already accepted as updates, we even uninstalled and re-installed the theme and these errors still persist, although the theme is processing less slowly now.
I already considered changing the theme, but I love the theme and would love to continue using it.
Could you help us?

The page I need help with: [log in to see the link]