Comment 10 for bug 134277

If you can confirm that the problem is solved with 3.6.0-13 than it is not a bug introduced upstream. Both 3.6.0-13 and 3.6.0-20 should be using the same upstream version (3.6.0).
Looking at the changelog:

http://packages.debian.org/changelogs/pool/main/a/atlas3/atlas3_3.6.0-20.6/changelog

there is nothing which immediatly pops to the eye as a possible cause to this.
Could you perhaps test by using 3.6.0-19, which is still available from the debian repository?