Well this was less than ideal. Kicked off my first training session with 20 participants and clicked on Share board to find I can no longer allow visitors. 
This cost me about 20 min trying to figure out what the heck was going on and the only option I had was to invite everyone as guests. 
Not great at all - the whole reason we use visitors is so that participants do not have to put in their email addresses and our account doesn’t get spammed with hundreds of useless accounts.
Is this a bug? Is this some new functionality that was rolled out? Have you guys ever considered feature toggles that I as an end user can control? As in… let me decide when I want the entire interface to change… let me decide if I want to try out the right click to move… let me decide when I want to turn on feature X that is super disruptive if we find out about it on the day it’s turned on?
