Complex bound name not being carried across _QLButton

Not high priority, I have a workaround, but for future reference.

Overview
1) I have a _QLButton.
2) Its QL binds a bunch of names, then creates another (inner) _QLButton.
3) The inner _QLButton uses a bunch of the bound names in a _notify call.

Some of the bound names work fine (yaaaaay!), but one of them results in an error ("_notify parameter body should be of type Parsed Text Type but is actually Value has not been set"). If I replace the bound name with exactly the same expression bound to it, there's no error.

Details
The bound names are

+$this-release
<.9v5kahj, .7w4geu6> -> +$notify-recipients
$this-release -> Name -> +$notify-subject
$this-release -> ""[[Notes]]

[[Downloads -> ""<a href="[[URL]]"><b>[[Name]]</b></a>"" -> _bulleted]]"" -> +$notify-body
It's the last one, $notify-body, that's causing the problem - whether I define it as above, or put $this-release inside the ""...."" block (i.e., referencing [[$this-release -> Notes]] and [[$this-release -> Downloads -> ....]]), when I click the QLButton I get _notify parameter body should be of type Parsed Text Type but is actually Value has not been set.

If I replace the bound name with the exact thing I was binding to the name, i.e.

_notify(recipients=$notify-recipients, subject=$notify-subject, body=$notify-body, thing=$this-release, topic=""Release"")
becomes

_notify(recipients=$notify-recipients, subject=$notify-subject, body=$this-release -> ""[[Notes]]

      [[Downloads -> ""<a href="[[URL]]"><b>[[Name]]</b></a>"" -> _bulleted]]"", thing=$this-release, topic=""Release"")
then it works fine.