textedit/pattr in Max for Live device

Apologies if I've missed this somewhere else.

I'm having an issue with pattr not saving values from a textedit, when set by an external and not actually typed by the user. There's some custom code involved so here's a screenshot / description :

The ptline external, when sent an empty string or NULL, will generate a UUID as a symbol, which I'd like to save across runs. If given a UUID, it'll instead use that - hence the pattr connection. What I've found however, is that while this patch saves just fine if I click in the textedit and hit return (thereby "setting" the text), but will regenerate the UUID if I save the set without manual intervention.

Is my patching logic wrong here? Is there any way I can force the pattr to update?