This has been fixed
When excluding folders in virtual appliance you need to use forward slash "/" and provide a closing slash at the end of the path
Omit the mount point when specifying Source files exclusion.
You can exclude files or folders from a backup. For example, you want to reduce backup size or time, some files are protected in another backup or do not need to be protected at all.
To exclude files from a backup:
If there are issues with the file system on the backup source, exclusions configured in backup options may not take effect. Files and folders are not excluded from the backup.
Issues with file system prevent Acronis and any other software from reading and processing files and folders properly.
Check if Windows reported issues with file system and then run a command to correct them.