The technical debt will change if you update the SQALE model. But that's not the only case.
The main remediation function used to compute the technical debt is "linear". This function is: tech_debt_of_issue = coefficient x effort_to_fix
The "effort to fix" is a value that can set by checks (Java class) that implement a rule which uses a threshold. But only few of those checks really feed this "effort to fix". The most common one is "Insufficient branch coverage": the effort to fix will be the number of branches that must be covered to reach the threshold set for this rule. So:
*If on analysis #1, you have 1 branch to cover, your technical debt will be coefficient x 1
*If on analysis #2 you have 2 more uncovered branches, your technical debt will be coefficient x 3
And there's only one issue for the whole set of branches, so adding uncovered branches accrues technical debt on the single, existing issue. So your technical debt will have changed and you shoudl be able to see this in the changelog.