Are you asking about the *Part Number entry box when you click +New to start a new E2E thread? If so, please follow the process of entering the part number, clicking on that part number from the drop-down list, then go to the next field of "*Is your issue . .". Don't click on other sections of the page, as you have noted, there is a "glitch" in the entry process that can produce this "part number not recognized" condition. If you follow the process as designed, then this will not occur and you can input your support request.
Do you have a support question you would like to submit but cannot do so? If so, would you be willing to try the process as described, and not click away from the designated input boxes? Please let us know the results, and if it is not working, the process you used.
At your service,