Hello CHANDRASEKARAN PREMARAJ Harish,
Thanks for your question.
Since it is intermittent it is most likely a browser issue, try clearing your browser's cache and cookies or a Different Browser: Sometimes, specific browser issues can cause problems with the Azure portal. Try accessing the Blueprint definitions in a different browser or in incognito mode.
You can mark it 'Accept Answer' and 'Upvote' if this helped you
Regards,
Abiola