You need to click where you see the sign "drag and drop photos here or click to browse"

nothing happens

when I go to Inspect Element on Chrome, I get this:

Uncaught ReferenceError: addNewPhoto549418a760cbd is not defined

Uncaught TypeError: Cannot read property 'keepTextCompleteDropdown' of undefined

net::ERR_CACHE_MISS

Inside, have you added new 3rd party plugins recently.
Definitely there's a javascript conflict.
Try to disable them one by one to see which one causes the conflict.

Aww :(

Ok, Ill get back with this issue.

could it be that mod_sec is enabled and because of that nothing  happens when I click on Browse?

ok, so mod_sec has been disabled and I have tried with disabling all of the plugins one by one - still nothing.

When I select Inspect Element in Chrome, the message says:

 Uncaught TypeError: Cannot read property 'keepTextCompleteDropdown' of undefinedjquery.textcomplete.js:301 (anonymous function)jquery.min.js:5 x.event.dispatchjquery.min.js:5 y.handlejquery.min.js:5 x.event.triggerjquery-migrate.min.js:2 e.event.triggerjquery.min.js:5 (anonymous function)jquery.min.js:4 x.extend.eachjquery.min.js:4 x.fn.x.eachjquery.min.js:5 x.fn.extend.triggerVM4153:501 _elements.dropArea.add.on.eventMap.clickjquery.min.js:5 x.event.dispatchjquery.min.js:5 y.handle

Can you please PM me your admin details for the website?