Well the debris field is technically not a comet’s tail...but the tail is behind the comet incoming to the sun due to Solar winds. On exit the comet’s tail is pushed ahead of the actual comet.
Now with that said...the nucleus was thought to be just a conglomeration of ice chunks. So when the radiational pressure of the Sun started to exert itself on teh comet it acts to destroy that bond and basically destroy or vaporized it’s core.
Are you saying the comet should now be pushing it’s tail in the SOHO images?