Due to upgrade to 2021 this weekend so fingers crossed 🤞
Also we upgraded my colleagues workstation to 32GB RAM in the hopes it would resolve the issues for them but it made no difference, so who knows what the issues was.
EDIT 19.10.20 - Updated to VW 2021 over the weekend - Happy to report interior elevations appear to be working a lot smoother and visualisation issues haven't been evident so far.