I also have the same problem (shown on picture) for version 0.5.1 for Windows. But in version 0.4.7 no this yellow things. Should be bug of v0.5.
As a temporary solution you can download v0.4.7, copy the folder: \save from the version 0.5.1 into the v. 0.4.7 and complete this quest there (don't forget to save at the end). Then copy the folder: \save (with completed quest) into the version 0.5.1 and continue gaming. This way you will avoid this bug.
You also could try to copy directly file with your saving instead of the whole folder (I didn't do this, so I don't know will it work or not).