you can even test it with the primeNg-demopage at: https://www.primefaces.org/primeng-7.1.3/#/picklist
drag and drop works with chrome - but not with Firefox (for example: Firefox 68.0.1)
another problem is: Multimark + drag and drop only moves the 1. element - not all marked (multimark!) elements. This happens in all browsers, even chrome.