Feature revert deletes existing Strongarm variable

Question

I got a Drupal 7 feature, which contains certain Strongarm variables, such as admin_theme. This feature has been created, released and reverted multiple times, always without fault. Suddenly, the last feature revert leaded to a deletion of some variables which are clearly defined in Strongarm.

The only thing that helped "a bit" was to remove the variables from the feature, release & revert them, and then add the variables again and release and revert once again.

This can't be a solution for the production release because this one has to work in one time. Why can it be that a Feature revert deletes variables from the database (variable table) which are clearly stated in the feature?

Answer 1

In case someone gets on this question: We finally managed to find the answer to our problem.

We had an old version of the strongarm module (7.x-2.0-beta2) instead if 7.x-2.0 which is stable now (since 2012). The update hook from this update saved a lot of variables from the features to the drupal variable table, and on every further feature revert, no more variables would be deleted, so the problem was fixed. Credits to @Weri!