Running Firefox 64bit version. So far, any Firefox after v63.0.3 won't allow Citi-Bank citi card virtual account numbers to function. Virt. acct #s uses Flash. I have flash enabled, but the virtual account number screen starts to build then just stops with no error message. I can then uninstall the newer version of Firefox and reinstall v63.0.3 and everything works just fine. Have not tried using the 32bit version of Firefox, but am considering switching to see if it works. For safety reasons, I prefer to use virtual (one-time) credit card numbers.