In Progress
When using geogebra cas if I plot for example f(x)=(x-3)/((x-3)(x+1)) it correctly shows the eliminable discontinuity at x=3.
If instead I plot f(x)=(x+3)/((x+3)(x+1)) it does not show the discontinuity at x=-3.
I've checked and it seems to happen with all the eliminable discontinuities in negative x's.
I'm working on windows 10 and chrome but I have also checked in the Geogebra Cas app for the mobile phone.
Thanks for your great work!
Anna
The same problem 
There's definitly a problem depending on versions of GG. I tried myself what you described in GG6.609 and there was no problem. I uploaded it and there too, no problem. Then I 'downloaded' theGG6-version as ggb, opening it in GG5 version 5.619 and there it didn't work while uploading... until I clicked on view and then again the command worked. Anyway I just checked that the commmand works in the webversion (Classic) for negative numbers too, so I guess it's a matter of using the most recent version.
Online working in https://www.geogebra.org/m/p99uknam
Online first not working until clicking on the View icon https://www.geogebra.org/m/kbvvmxe3
Added the file that didn't ork in GG5.619 for me. Perhaps opening it in whatever version it work...
Thanks, we'll fix that soon!
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