ATrousWaveletTransform is an obsolete process, so it has not been included in the update that we have released to fix this problem. ATWT will work correctly in the next version of PixInsight (1.8.4.1187, almost ready for release on Linux, OS X and Windows), but it should not be used in new projects. It is kept only for compatibility with existing projects, and will eventually be removed from the official distribution.
Please use the MultiscaleLinearTransform tool, which has superseded and replaces ATrousWaveletTransform.