Cal here from Shopify, thanks for reaching out to us. That sounds like a browser/cache related issue! Can you please try logging in using a different browser for me? Alternatively, can you clear your cache?
If that doesn't work, can you attempt logging in via a different device? Even a mobile device would suffice, we just want to test the login process for your store.
What is the MyShopify URL for your store and I'll test the site here myself? Thanks!
That sounds like you need to clear your cookies from Chrome. You can do so by following this guide. Let me know how it goes!