Recently, we upgraded our Google Chrome into Version 65.0.3325.146 and suddenly all the quick create forms are not working properly anymore but it is working with other browsers.
We tried to clear cache , disabled all JS, unfortunately the luck is not with us.
After spent some time to debug using F12, it seems that "mscrm-globalqc-iframe" is not having correct value while compare to other browser.
So temporary you can use below code until the future update. But please note that, the below code is unsupported, use it at your own risk.
If you decided to do it, Register the below function via on load event in all the quick create form.
Else temporary advice your user to use other browsers first.
var isChrome = !!window.chrome && !!window.chrome.webstore;
if (window.top.document.getElementsByClassName("mscrm-globalqc-iframe").style.height == "0px")
window.top.document.getElementsByClassName("mscrm-globalqc-iframe").style.height = "160px";