If you go to the LetsEncrypt forum, create a new topic in the Help category, and fill our the form you’re presented with, they can check your domain(s) and tell you what, if any, problem(s) there may be. They can also help you to correct any problem(s).
As an aside note: LE recommends using the “staging” modal to avoid hitting certificate limitations that you encounter in the production mode. A limit of 5 failed tries is refreshed after 1 hour. 
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