Hello,
Thank you for pointing out the celltype category. We did some readjusting of categories that removed the cell-type on accident. This has been fixed. If you are using the website, you may have to reload cache to make sure you see the updated version (cmd + shift + R on mac, ctrl + shift + R on windows/linux).
For the GO analysis, nothing should have been changed and I am still able to perform the GO analysis online. What species are you using, and are you using the R package or the website?
Best,
John