We have 2 computers in our store. From one computer both of my Shopfiy users (myself and one other) can log in to Shopify, but from the other computer, only one user (me) can log in.
Both computers were bought at the same time, run the same software and are maintained at the same time by out external tech support people.
You can also try logging in via another browser. For example, if you’re using Safari, you can try logging in via Chrome or Firefox
If you’re wanting to check on your usual browser, you can also do this but to clear the browser’s cookies and cache before you login to your store
You can also try to use another device, such as your mobile or a tablet, just to check if you’re able to login successfully on other devices too apart from your one computer
Let me know how this goes!
While we’re here, I’d also like to hear about your store! Have you just recently opened your store?