I've been in similar situations in the past. When there's a communication problem, this tends to be very frustrating for both parties: you're not getting your thoughts across, and the other person is frustrated that it's taking them so long to get their information. It's easy to get lost in your own side of the argument, since to you, it seems like you're crystal clear in your communication, how could it be misunderstood?
The trick is, that whether or not you're right is irrelevant. Your goal is to work together with this person. This means that you need to communicate in such a way that they understand the message you're sending. So, start your conversation from that point of view, taking care to use a neutral tone without any hints of sarcasm:
Hey X, can I get some advice from you?
I'm having trouble finding a way to convey things to you in the right way. Last [day I was working from home] for instance, you wanted to know about two things. After I thought I had answered, you later asked the same question again, which leads me to think that I hadn't succeeded in properly conveying the information to you. Here in the history, you can see the format I used to try to answer. It seems apparent that I'm not wording this right; how can I word this in a way that makes sense to you?
If the case is truly as you describe, the answer will hopefully be some awkward shuffling on the part of the other person, followed by a concession to be more careful when reading your replies in the future.
However, there is a good chance that you will be surprised at the answer. If there is an actual improvement to be made, the other person should be able to suggest a way for you to send the information in such a way that they can easily understand it. As the sender of the information, you already know it, so it's easy for you to read your answer and get the information from it. This may not be equally simple for the other party.
Either way, you've taken a constructive approach to the issue and you're not blaming anyone. If the other person suggests a new way to communicate and it's still not working, follow the same routine: raise the issue in a neutral way and look for a solution together.
It may seem like an injustice when in a situation like this, you have to put in all this effort when you were being perfectly clear in the first place. While that is true to an extent, in life in general but especially in the professional world, it always pays to be the 'bigger person'. Your life will be much easier if you're using this sort of methods to solve your problems because you'll get a reputation of being easy to get along with and easy to work with. Especially in the corporate world, competence is not always the most important aspect that decides one's career path. I've seen relatively incompetent people get raises and promotions over others, simply because they're easier to work with.