I assume you mean that you left a comment under an answer to ask for clarification. I looked through your comments and many of them looked like statements, not questions or requests for clarifications. In these cases, I wouldn't expect a response because there isn't really anything to respond to.
I saw one example where you didn't receive a response (here):
Not sure how "exacerbate" resolves my query. My main question was how to emphasize that the unrest was for sure going to be fueled by unemployment, and that the threat was not fueled by existing unemployment.
In this case, it looks like you left that at 2018-09-01 09:12:49Z, but the last time that user visited the site was 2018-09-01 08:13:02Z. So I don't think they've seen your message yet. When you see a date or time on SE, you can probably get a timestamp if you hover over it. You can see the last time a user visited by visiting that user's profile page. It will say "Last seen".
It also helps to @-ping someone when there are multiple users. Just type
@username. The person who made the post under which you left a comment always gets a notification. So you don't need to @-ping them. You can see more details here: How do comment @replies work?.
As for some general advice, make your request for clarification clear. Say something like,
- Could you please explain what you mean by Z? or
- I'm not sure how this solves my problem. Could you clarify?
similar to what you wrote above. If you just make a statement with no indication that you want feedback or clarification, the user may not respond. By the way, check their answer. They might have updated it, but didn't leave you a comment.
Also, give the user at least a day or so to reply. Yes, they might have just answered your question. But they could have easily left immediately after. That's not uncommon. Or, maybe they just don't want to respond at that moment for whatever reason. Maybe they're busy. Maybe they can't articulate their thoughts at that moment.
Keep in mind, it's easy to forget about responding. It's not like this is a pressing business relationship. Using SE is recreational, so it's easy to forget about a comment someone left. After giving the person a long chance to respond, you can try giving them a friendly reminder:
Hey X, I was wondering if you had a chance to look at my comment regarding Y. I'm still interested in hearing what you think.
If you gave the user plenty of time and a reminder and they still haven't replied, then I suggest moving on. They may not be interested in or committed to helping you through the end. It's unfortunate, but it happens.
Keep in mind that comments are not meant for answering more questions. Sure, the occasional, brief follow-on question is fine. But think about the problem. If it could be answered in more than a few lines, or if it's part of a larger problem you have, then consider posting a new question.