Not sure if this is a bug or user error:
At one point, there was a transmission timeout setting that I set to 60 seconds, so that after 60 seconds the scanner resumed scanning even if the transmission was still in progress (to prevent the scanner from hanging on unrecognized control channels and suchlike). I want to change that to 5 minutes, but the setting UI seems to have disappeared, and I can't find any reference to it in the manual. It's independent of the max record time setting; the scanner resumes scanning after 60 seconds regardless of the max record time setting, and regardless of whether recording is enabled.
I was using a 436 with ProScan when I set the setting, and am using a 536 now, if that makes any difference.