unless I am remembering incorrectly, and I don't think my applications were that long ago, the letter recommendation is part of the standardized application. And until every part of the standardized application, both submitted by you and submitted by various administrative bodies, is 100% completed, the AAMC and AACOMAS will not send out your application to the schools. basically, when you go to fill out that gigantic application, if there is a tab for it, it needs to be 100 percent done or else nothing you fill out will be sent forward. And I'm very confident, but not absolutely so i will not 100 percent guarantee, that there is a tab for your letter of recommendation where it acknowledges if its been received or not, similarly to how there is a tab for all of your transcripts.
if that tab exists, then I would assume I am right. If it doesn't exist, and I am remembering things wrong and I apologize.