Warning message - "DEVICE=>HEAD" transformation

Bugs
1

Hello

When I tried to import a FIF file of a run in a session of MEG experiment, I got the following message:
The "DEVICE=>HEAD" transformation is missing in FIF file. Maybe the HPI coils positions were not acquired correctly.
Using a default transformation instead (4cm translation in Z). The head will not be properly aligned...
I can import all other FIF file of the session without any warning message. Is something wrong with my data or it is a bug with Brainstorm?

warning

I am using MATLAB R2019a and Brainstorm 3.201026 (26-Oct-2020). My OS is Ubuntu 18.04.

2

This indicates exactly what the message says:
The "head" coordinate system is not defined in the FIF file, the information of where the head is in the MEG was not computed or saved by the Elekta acquisition software, either because the HPI coils were not localized correctly, or because the acquisition software crashed at some point.
There is no bug here, but a problem with your file.