Hey John, have you tried playing with the live link settings when syncing from Archicad? Playing with the optimization settings in this window might help. Also, is your TM updated to the latest version (2021.1.1) ? Alternatively, if you are able to send me a link to your AC file, I'll be happy to look into it further on.
AC27 ARM // MBP M2 Max // Twinmotion | Corona | Rhino