App Store Connect: "Ready to submit" builds are not available to submit for review

In App Store Connect under Testflight section I can see multiple builds with status "Ready to submit". When I go to App Store section, click on the version of the app which I want to submit, scroll down to the Build section, I dont see any "plus" button I normally see to select the build I want to submit for the review. Just to clarify, the builds that I can see under Testflight section that are "Ready to submit" are the same versions as the app version I open under App Store section when I want to submit app for the review. All I can see in that Build section is "Upload your builds using one of several tools. See Upload Tools".

Could you please let me know what this could be caused by? I have sent for review around hundred builds of several apps before and never had this issue.

My deployment target is iOS 11.0 and those "Ready to submit" builds are not expired.

Thanks for your help!
App Store Connect: "Ready to submit" builds are not available to submit for review
 
 
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