Quadralay support has since confirmed this defect, which they describe as follows:
If your AutoMap job does not complete successfully, and it returns errors in the log regarding failed communication with FrameMaker, it’s possible that it was not able to run the job from the Windows scheduler (even if you are running it manually) due to invalid credentials.
That is, when you set up a job, you must provide a valid user name and password to schedule the conversion. If a job is executed, and it can’ t log in correctly, it may report errors in communicating with FrameMaker (because it can’t even communicate effectively with the system). To resolve the issue, right-click on the job in the AutoMap interface and choose Schedule Job. If you’d like to schedule it for automated conversion, do so in the Windows task scheduler dialog that appears. Otherwise, just click OK. You’ll be prompted for a user name and password. Enter the correct credentials, click OK, and then run the job as usual.