Difficulties to link TestCases to Releases automatically by TestSet way

We've created a lot of TestSets automatically from Requirements and Linked the TestSets to Releases/iterations. Unfortunately, all the TestCases inside a TestSets are not automatically linked to the release choosen for their TestSets. We have to start a run "artificially" (Start then Finish just after) to have the link created. By this way, the release summary of the project home dashboard indicates the right number of tests planned for each iteration.

It would be too difficult indeed to opened each testcase to mapped the good release/iteration....I don't understand why the links between the testcases of a testset and the releases/iterations are not done automatically as soon as the testset is linked to a release.

Regards