This happens because of the unexpected extension.
Brainstorm uses either the old or the new InTan reader, and the selection of the reader depends on the extension of the file. .rhd (new reader) or .rhs (old reader).
In your case, for an arbitrary and unclear reason the extension of the Intant files is changed from .rhs to .edf. So, no reader can be chosen for that file.
FYI. This error is not possible through the GUI as Brainstorm verifies that the extension of the files matches the file format.