Hyde here from Shopify.
That is certainly very strange! Before we assume a technical issue, could I ask you to try accessing your store admin:
1. On a different browser
2. In incognito mode
3. On a different device
4. On a different internet connection
...and let me know after trying all that whether the problem still persists. My thinking is: because it's not a platform-wide issue, it is probably a localized problem, related to either your cache and cookies or your internet connection or the device you're using.
I look forward to hearing from you!
All the best, Hyde.