local variable being reset from outside of script

[Dr. Hawkins]

In the script of a behavior button for a field, I have a block of

    *if* pChFld is empty *then*

         *breakpoint*

      *end* *if*

      *palette* chStk

      *if* pChFld is empty *then*

         *breakpoint*

      *end* *if*

where pChFld is declared local outside of and before any handler.  This is
also the only script anywhere with a pChFld.  pChFld contains an id for a
field in chStk, and strict compilation is on

Supposedly, pChFld will be persistent under such circumstances.

Somehow, between the two checks, pChFld changes from holding an id to empty.

I have single stepped through the palette statement; there is nothing there.

I have tried changing pChFld to a global; no difference.

I've wrapped the palette statement with a lock messages/unlock messages, no
effect.

If I single-step through in the IDE, though, it all works, and pChFld .
For that matter, if I put an evil red dot on the first if in this block,
and then let the debugger run from there without single-stepping, it works.

I'm seeing this in 7.0.5 & 7.0.6-rc1 on yosemite

 Have I hit an ugly bug, or am I missing something?

-- 
Dr. Richard E. Hawkins, Esq.
(702) 508-8462