A family of Microsoft relational database management systems designed for ease of use.
That's good.
What we need to know as well are the answers to my other previous questions about what that "mirror copy" is.
In particular: "When you say you want a "mirror copy of [your] sql database, I assume you mean duplicate tables in a local accdb. Or do you mean a local MySQL database?"
We can infer, probably, that you mean you have tables in your local Access accdb which are the same as the tables in the MySQL database.
Is that correct?
Can we also assume that your local accdb has links to those MySQL tables? If not, please be specific about how you try to retrieve the data, not just "...playing with settings" which provides no actionable information.
It appears that the update to your local tables is successful sometimes. Sometimes there are errors, though. Please show us the errors! That'll help someone understand the reason for the problem and help diagnose the problem.