Thank you for reaching out in the community, I see that you have an existing case with us regarding this as well. if you are still experiencing this issue, can you please update your bug report? We'll have more information on managing your cases here: Twinmotion Community - Case Management
If you are experiencing the issue moving project files between computers, it can be helpful to use the Resource Collector, we'll have documentation on this available here: The Resource Collector
If you are experiencing the issue on one computer only and not when moving the file between computers, I believe this may be due to an issue with the permissions of the drives/folders your files are located on. If you would, please ensure the file locations have the appropriate read/write permissions so that they are able to be seen by your Twinmotion file. Please see Apple's article here for more information: Change permissions for files, folders, or disks on Mac
If you continue to experience this issue after, please follow up with your existing bug report ticket or create a new ticket with us using the Contact Us button here: https://twinmotionhelp.epicgames.com