Hi Evangelos,
Indeed that was introduced recently:
https://github.com/brainstorm-tools/brainstorm3/commit/efb2fcd483beedbc78074dc0b44199956605a86d
Did you update Brainstorm by pulling from GitHub?
Can you try to update Brainstorm from the GUI?
- Menu Update > Update Brainstorm, in the main application window.
- Restart Matlab after updating the software.