I seem to be experiencing this and see a history of similar problems - but nothing recently.
Verion 2015r2.4, windows debug and linux build.
New clue: when set to multiline mode, the content appears on the labels. When not in multiline mode, content does not appear.
Other info: when setting a style, the background color of the style does appear for the label, but the content (text) does not appear - regardless of which colors I choose (so far).
Yes, but fonts may not be installed on the server, so that will be a problem especially on most Linux hosts.
The other workaround is to use a Read only TextField styled with a transparent background and borders width 0. It will use client side fonts, so you can use any typeface family.