Hi Alessandro,
Thanks for writing in! I have tried to replicate this issue on Integrity theme, but I couldn’t. Could you please try removing your custom CSS and JavaScript added to your site temporarily and see if you can find any conflict.
Further, I would suggest you to disable your 3rd party plugins as well and test this issue further. If the issue resolved, you can then activate your plugins one by one.
Also it could be related to your child theme customizations as well. Try disabling it temporarily by activating your parent X theme by head over to Appearance -> Themes section and see if the issue resolved.
If you cannot isolate the issue, you can use the temporary workaround mentioned in your post above.
Thanks!