Hello Ignacio,
Welcome! No, this is not an error. For computational methods like DFT it is common to specify the positions of every atom in the unit cell explicitly rather than specifying the spacegroup symmetry operations. Computed, primitive, and conventional unit cells on the MP will show triclinic (P1) symmetry (i.e. ‘no symmetry’) in the cif file because the symmetry operations are not specified. If you determine the spacegroup with a spacegroup analyzer (e.g. spglib or AFLOW-SYM) it will show the correct spacegroup though.
Regardless, if you still need the cif file that defines the atomic positions via symmetry operations then you can download it by clicking on the cif button and select Symmetrized.
Here you can find some additional information on the cif file types - hope it helps!
Best,
Peter