CellProfiler development is discussed on the cellprofiler-dev mailing list. This is a fairly low-volume mailing list. To subscribe:
https://groups.google.com/a/broadinstitute.org/d/forum/cellprofiler-dev
Most users should use the CellProfiler forum to ask for help and report issues. We monitor the forum and may be able to help you find a workaround for the problem. If you have discovered a new bug, we will take care of filing a bug report on your behalf and include all necessary technical information.
The issue tracker on Github is primarily for developer of CellProfiler and related software. There is a special form for submitting new issues with attachments. If you use this form for reporting bugs, please attach sufficient information to reproduce the bug. For many bugs, it is appropriate to attach a CellProfiler pipeline and an image.