When Skyline can't find a protein in Uniprot it then searches Entrez on the chance that it's an older style of protein description, something which Entrez handles well. If that succeeds, Skyline then uses the Entrez result to go back to Uniprot for the rest of the information. Interestingly the proteins in your data match at Entrez but the results don't have a match at Uniprot, something I hadn't seen before. The bug is that Skyline keeps trying when it should really just give up once it's apparent that things just aren't working out.
We might also want to just remove the status bar update for this background task, though as a developer its presence is useful since it allows users to alert me to issues like this.