I often find that students go directly to their mark and where they have lost lost marks.  It is easy to discuss this face to face, but doing remotely has it's own specific problems.  Tutors may not be available when the marks are released and some students might want to discuss them there and then.  Feedback maybe misunderstood and email can often be slow. 

Sometimes you may find you don't understand a piece of work and it may delay marking until you can discuss meaning with the student. Also, some marking and results might be down to how specific criteria have been met, rather than reflecting the quality of the work overall. It may be disheartening for a student to initially see marks online, without a supporting conversation.  

Being a new tutor, I would be anxious about the differences in strong and weak students may make my feedback. I sometimes have just ticks in my answers and a summary feedback. But when I have had a bad answer, the tutor corrects it in different colour and explains where I am wrong. Then, I get advice on how to prevent these kind of mistakes.

I think communication is the key with marking distance learning. As an OU student myself, there have been occasions where I have wanted to ask questions about certain feedback I have been given, which is more difficult when you are not with your tutor in person. However, if channels for communication are kept open and the student is given an opportunity to discuss feedback if required, this would hopefully resolve that issue. 

I'm used to 'classroom' teaching where the students see their marks and can ask questions. Via correspondence, it would be necessary to try to preempt those questions and provide answers proactively.

For me, one issue could probably be the ease to which the given feedback can be explored further through communication between the student and tutor.