Please make sure all the settings are exactly the same, in particular the source spectrum range. this huge difference looks like due to Linux file uses the default wavelength range while in Windows file uses much longer wavelength. Ideally, it is better to copy the file from windows to Linux to ensure all the settings are exactly the same. In case you copied and the problem still exists, please send us an email with the post linked so we can have a careful check, as the forum does not allow us to check the customer files.
In addition, Lumerical has a dedicated forum here:
please post your questions in the Photonics category. Otherwise your post may be delayed for a reply.