My watermarks are not showing up now when I export my photos from Lightroom. I just got a new update from the Creative Cloud. I went to put some of my photos on Facebook and noticed that the watermarks are not there. They show up when I add them on the photo, but once it's exported, they are gone. This has never happened before. Can someone tell me if there is a bug in the latest version of Lightroom?
There is no such bug reported with the latest update of Lightroom CC.
Would suggest you to reset preferences and recreate your watermark and then, check.
Refer this article for steps to reset preferences : Resetting (or 'Trashing') the Lightroom Preferences file | Lightroom Forums
There is a current bug where if you go into the Watermark Editor, as you exit the WME it'll blank out the previously selected (and edited) watermark, but all you have to do is select the correct WM from the list, again, before exporting. If you're going in and editor and changing something with each export then maybe that's what is occurring.