page builder issue

Hi I’m using Maskitto light on two websites and everything was working well. I didn’t make any changes apart from updating wordpress and plugins, but it’s about a month that I’m having troubles with page builder plugin. The file activation.php in inc folder keep disappearing and I need to upload it every day in order to make the sites running, otherwise it returns a 500 error.
I use page builder with other themes and there are no issues with them. Any idea of what is wrong?
the sites are http://www.accademiamusicalestradella.it and http://gliamiciditeo.it
thanks