Same for me PC / Single mode. After patching to 1.0.5, but have seen him already in 1.0.5 previously.
Cannot see him anywhere over lab windows...
My last actions - wondering at garbage area (blocked black ants stock piling), retriving labirynth chip (table top), wondering at BBQ. Previously seen BURG.L not in the centre Oak lab but stuck before main lab doors in the entry corridor (downward broken one) - could interact with him normally there.
Will send a save file via email.