We usually do not recommend to limit solution attempts because does not reflect the workflow of a take-home project or debugging in industry. What kind of problem are trying to solve by limiting submissions? Students can always access their previous submissions and make sure that their most recent attempt reflects their best work.
The hosted version of MATLAB Grader allows you to export a history of all solutions or the best solution. However, the gradebook/completion status always showed only the latest attempt as in the MATLAB Grader integrated in Moodle. We do not currently have an export of all solutions in the LMS version. In a limited submission problem, the only workaround we can propose is to ask that those students where the most recent attempt is not their best work, to share their solution ID for a better solution. You can then query the solution report based on this ID, visually inspect the solution proposed and overwrite the grade in the gradebook.
