'Add all open tabs to collection' option is gone; when you right click on a tab it used to be at the bottom? Help?

Sorry, it is not wrong, what has happened is that the change is forced to personal microsoft accounts. When you log out of your account on Edge, you will have the "old style" collections experience, just as if you logged into a work or school account.

Again, you need to be logged in to a personal account to see the new experience. If any other condition is true, you won't.

Incidentally the add all option is not the only thing that changed. Poke around and you will find other options that are missing or actually are bugs that don't work.

Wrong, collections was auto-upgraded for all users to the new version. There is only one version of it. It does not revert to a different or previous version when you log out, it just gives you the add to collections option back for open tabs.

It's only a bug if it's not by design. Just as I said earlier and Hermes confirmed, this is intentional at this point.

I think it probably is still a bug. There is no reason not to have the menu option 'Add all open tabs to collection' when using Bing Collections.

This is not a bug per se. It's a different product that was rolled out to personal accounts. If you're logged in with a Microsoft personal account, you are forced to use Bing Collections instead of Edge Collections. You'll know you're using Bing Collections if you see random pics (ads) on the Collections pane under the new "Start to Collect" area. Your data is now on the cloud and available to content creators (advertisers) thru Bing. If you're signed out or logged in with a work or school account, then you'll be using Edge Collections which has the functionality you need.