disappearing syntax properties in DrRacket 7.0.0.7 REPL

Consider this language that accepts one expression:

;; lang.rkt
#lang racket
(provide (except-out (all-from-out racket) #%module-begin)
         (rename-out [mb #%module-begin]))

(define-syntax (mb stx)
  (syntax-case stx ()
    [(_ EXPR)
     (with-syntax ([PEXPR (syntax-property #'EXPR 'foo "bar")])
       #`(#%module-begin #'PEXPR #,(syntax-property #'PEXPR 'foo)))]))

(module reader syntax/module-reader
  "lang.rkt")

And a file that invokes it:

;; langtest.rkt
#lang reader (submod "lang.rkt" reader)
"string"

When I run langtest.rkt the first time, a syntax object is printed to the REPL with an info box like so, followed by the value of the foo property:

But when I run langtest.rkt again, the Original? property changes to #f , and the custom foo property disappears from the info box, though it still prints to the REPL:

This seems wrong.

After that, I can only get the correct (initial) info box to show up again if I quit and restart DrRacket. (In particular, changing the #lang line, or using Reload #lang extensions, has no effect.)

Reproduce the behavior with the lang.rkt and langtest.rkt examples in DrRacket, running langtest.rkt twice and observing the syntax object's info box. Trace where the REPL or editor retains syntax properties between runs. Done means the custom foo property and Original? state remain correct without restarting DrRacket.