It is interesting that I can find the missing tags in the site discussion section but I was unable to pull up the 858 tag for the current weekly challenge. When I added the number 858, it was not recognized as a tag. I tried multiple times and multiple approaches to enter this number but it was not accepted.
David, although I did not add a photo I was able to add 858 in the Tag selection in the WC Gallery. Again, as I did not follow all the way through with the post it at least let me add that to the Tag window?..
EDIT: I did actually add a photo and think I saw you had also. So, all is good I would think.
Strange, not sure how the setting got changed but I have fixed it and you should be able to tag now.