Divi Gallery randomly not visible at page load

Hi, I'm having a weird issue with my project pages were I have a Divi Gallery module.
When I load or refresh the page, very often the gallery is not visible in a random way.
I'm becoming crazy and cannot at all understand what the problem is, the gallery module has been used just the standard settings.
Is someone able to advise or has already encountered similar problem?
If you want to check the issue, you can try to see it here https://robertogenazzini.ch/project/cose-del-mondo-geson-e-dalila/ just be aware it's random and it's not necessarily easy to reproduce.

Thanks in advance for your help.

 

I've just put in your fix, since it's very random I'll have to test it for some time.
I actually had tried similar CSS fix on the parent but not on the items, so this is super promising.
Thank you so much, I really appreciate it!