I think the 3 octave response is correct. Mine does it also... as does the Pro-1 (doube check yours). I assume its becasue the originals only had to track over the 3 octaves of the 37 keybopards... so the electronics arent designed to be in tune across 88 notes. ENH is ENHanced mode on the original, which is a PWM with its own LFO I'd expect off to be no waveform, as on the OG. I think saying its a sine on the manual is an error - I never received any manual with mine Looking for answwers here myself.. Mine is retriggering randonly on MIDI note off - have you had any similar issues?
When VCO 1 is in LF mode (low frequency) it's acting like an LFO, so it will only produce very slow clicking - it's not meant to be heard in isolation but used as a modulation source. If you're really new to the synth this might prove useful. It's a walkthrough of the Odyssey for beginners I made a couple of months ago. I can't ost the lionk but if you google starsky carr ARP ODYSSEY:Tutorial and Demo you should be able to find it. Hope that helps :)