Comet display incorrect?

Rolf Stadelmaier Dec 25, 2018

Hello all,
when I hunted about older comet images and diagnosed the comets position, I experienced a never before seen incorrect display of the comet in Guide9.
I noticed that in case of comet Johnson (C/2015 V2 - 2017-05-17 22:34:48 UTC) Guide9 displayed the comets position with some offset and - and this was what startled me - the tail showing in a total wrong direction in comparison to my images.
Comparatively I find the display of comet 21P/Giacobini-Zinner (2018-08-16 21:15:24) in total accordance with my images.
To clarify what I found I uploaded some graphics here.
Have others experienced such unexpected behavior of Guide9 too? And is there a clearing explanation of this riddle?
Thanks for noticing,
Rolf Stadelmaier