When assigning tasks you can typeahead and click your mouse on the user, when you select the user using this method the assignment field stays active and you have the ability to add additional users.  If you're trying to do it without clicking the mouse you might have to use teams and then assign th...

I would recommend ensuring that everything in Workfront is configured for the individual - notifications wise.  If you are sure that Workfront is sending out notifications then it would be a matter of your email client doing something with the email (sent to junk) or a corporate routing situation.  ...

Echoing this statement, I would encourage the users to take a look at their individual notification preferences

Have you considered using Frame IO which seems to be built for this purpose?

Your system administrator might need to review the attached settings

On an administrator level you might want to check the attached settings

there's always https://www.brandsoftheworld.com/

Can you create a report which isolates all of the old data and then using that report bulk move the values from one to the other by editing?

I searched for "Adobe Workfront Press Kit" and this is what I found, hope this helps https://news.adobe.com/newsroom/multimedia/default.aspx

It could be that users are being directed to or are using the specific login url.  When our users authenticate through Okta they authenticate once centrally and then you are able to just click on the other apps and access them.  We do not see login screens for individual systems this way.