iwpt_compile broken for iw_include PTs in 6.7.1?

System

we upgraded to 6.7.1 recently...our templates worked perfectly before the upgrade...now we've got some intermittent misbehaving going on, which I'm trying to troubleshoot...

the content will generate fine through the GUI...and also regenerate fine through the GUI...however, if I use either iwpt_compile.ipl or iwgen, it bombs, saying "Could not process template: d:/iw-home/custom/pt/today/story.pt"

our actual TPL in the /presentation directory is simply one line:
<iw_include pt="d:/iw-home/custom/pt/today/story.pt" mode="ptlocal"/>

it still works from the GUI, so it doesn't seem that the actual iw_include functionality has changed, but I don't know why it's hating our setup from the command line now?

anyone else have this problem or any ideas?

thanks,
-Rori