I found the transaction set with ID 5010 and i am trying to understand
I've had a few similar issues. Usually, when I get an error like that, if I re-import the package using Validate only, it will show success, then do it again with 'validate and apply' - and it works.
If that doesn't do it, you might have a metadata corruption. One question: even with that warning, did the change show in your UAT? A warning does not mean it didn't import the transactions.