When you completed the upgrade to MM Premium 2023 did you also install all the additional content that comes with it? I'm not at my normal desktop computer at the ,moment but check under Help for a link, or check the Downloads and/or Store tab in the app.
@Ken-Malherbe Reinstalling is an option. You can redownload everything from the in-app-store. I'm not sure why it crashes now. Could be a graphics driver problems. Are you using multiple monitors? Maybe disconnect all but one. Or update your drivers.
Thank you for your comment and I apologise for the delay in responding to you (our country is having hectic loadshedding (blackouts) presently) and finding the time to sign on etc is frustrating.
I do not have any external audio device attached to my computer apart from my M-Audio keystation but the problem persists whether the keyboard is connected or not.
Some VST3 programs but some don't.
Not too sure of what further I can do apart from deleting everything and downloading MM Premium again or asking for a refund of my money.