Existing users are not prompted to update app on iOs app store

I created a new version for my app (3.0) and I released it on the app store. My update was published about 9 hours ago. However, when existing users open my app's page on the app store, there is no prompt to update.

When users attempt to update the app on the app-store, they see 'OPEN' rather than 'UPDATE'. If they click on 'OPEN', the old/existing version of the app pops up.

Here's a snapshot:

PS: The update is basically a logo change and since the new logo is reflecting on the app store, I'm sure the update has been done.

What do I do?

This issue corrected itself roughly 24 hours after the update was published. The text on the app-store page changed from OPEN to UPDATE and I was able to update normally.

The cause of this delay lies in the fact that Apple has many servers all over the world that need updating. However, if the delay is too long, consider contacting Apple support.