Sorry to hear you are having a problem. Walmart changed their app over a month ago. Have you opened a request yet?
You might try to unlink and relink your Ibotta account with Walmart. Go to Account, then Settings, then Linked Accounts. If Walmart is not listed or it says Connect, you are not linked. If it says Disconnect, it thinks you are still linked. Press Disconnect and then re-link your Ibotta Account with your Walmart account. Make sure you tell Ibotta the email address you use for Walmart.
If re-linking doesn't work, then you will have to open a request. To open a request, go to Account in the app, then Help. Unfortunately, waiting this long may require a lot of work on your part. Ibotta Care will need a copy of your emails from Walmart and pictures of the products and their UPCs. If you have multiple shopping trips, I would put each one into a different request. I would start with the oldest one. Please be aware that it can take 2-3 days for a response.