[BUG] org-element loading fails with "regexp" argument not "stringp"

[Justin]

Using emacs 26.1 (in case it matters).  Loading is failing at:

(defconst org-element--current-element-re
  (rx
   (or
    (group-n 1 (regexp org-element--latex-begin-environment-nogroup))

rx is a macro, and so org-element* is not being evaluated.  It's 
complaining that the argument to regexp is not a stringp.

Does the rx argument need a backquote?  org-element-clock-line-re uses 
rx-to-string with a backquote?

(rx `(or (group-n 1 (regexp ,org-element--...

-Justin