Export midi track to audio

Been using Cubase/Nuendo for years. Currently Cubase 8.5 on an old IMac. Was using El Capitan. Just went to Sierra 10.12.6 (Yes, way behind the times).
Can only export midi tracks to audio by using real time export. Computer freezes if I try to do it otherwise. Aside from getting a new computer and new everything else, any suggestions? Thanks.

Hi,

Where are there MIDI tracks routed to? Virtual Instrument or hardware synth? If you are using hardware synth, it must be processed in the real time.

Make sure you have the latest Cubase update installed. You can also try to trash Cubase preferences.