Sharing buttons not showing up

Hi!

I configured the plugin a while ago and it was working perfectly, but since a couple of weeks it stopped. Icons are not showing up, but they are there.

http://feverup.com/blog/madrid/cosas-que-odias

They’re placed after the title and after the post. When the page is charging, buttons show up for a few seconds, but then they disappear and just a blank space stays instead.

My buttons are custom ones, so I don’t know if it may have something to do with the problem.
I’ve already unactivated and activated the plugin, but nothing happens.

Thank’s in advance!

https://ww.wp.xz.cn/plugins/simple-share-buttons-adder/