Most times I try to use it, it says "Securely signing you in with express checkout..." and never gets any further.

Same experience as others. When I clicked on the Eno icon from my Firefox toolbar, the CapitalOne login window will open very briefly and then close. Eno only works if you first log into your CapitalOne account in another tab.

Stopped working a couple of months ago. Pops up saying "Checking Session" and then says you need to log in. After clicking to "Log in with browser" a window opens, then shrinks, and disappears. DOES NOT WORK

Exasperating!! just got an error message saying "Your ebay purchase was declined because you used a virtual card number you created for ebay... Use a virtual card number created for ebay to retry this purchase." ABSURD!!! it fails more often than it works, I give up. I'm taking it off my extensions.

No longer working after update. It always tells me to sign on by browser. However the pop up opens then shrinks and disappears each time.

As many other users mentioned, this stopped working the last time Capital One put out a new version about a month ago.
For me, when I click on the Eno logo and "Checking Session" appears, if I need to sign in a new window pops up for the login but then immediately shrinks and closes with out giving me the opportunity to put in my credentials. I was able to make it work again for 2 uses by uninstalling and reinstalling the add-on. Also, the work arounds others mention, go sign into C.Ones website, then open a new tab (or three) on the same retailer allow me to struggle through.
Honestly, I may drop Capital One if this isn't fixed, there are competitors with apps that work.

PLEASE MAKE IT WORK WITH FIREFOX!

THE WORK AROUND WORKED FOR ME - As with other reviews here, the ENO add on quit working easily - when I went to add a new virtual card, I had to sign into Capital One and then all it did was take me to the page that showed all my virtual cards BUT THEN I followed the advice of another review and logged into Capital One first, went to a website I wanted a virtual card for and ENO popped up automatically and created the new card. I gave three stars bc having to login to Cap One first shouldn't be a requirement but I LOVE the virtual card.

Plug in started blocking all content on multiple pages, some merchants some non-merchants (blank pages load with plugin enabled, content loads when it's disabled). Also doesn't remember login details.

Was on phone with C1 tech support. After explaining the issue multiple times, the call randomly went dead (no audio), before they understood the problem.

The app used to work fine. However, as of 10/25/21 it just pops open a window showing my existing virtual cards but doesn't allow me to create a new one.

Great when it works but way too often it tells you to sign in and doesn't recognize when you do. SUPER-frustrating.

virtual card will not add new maechants

Used to work, now broken as other reviewers have noted.