If I include the space group on the CRYST1 card of the PDB file all is well for non-centrosymmetric groups but when a center of symmetry enters the picture all bets are  off.

I'm using Tool->Higher-Order Structure->Unit cell

For example adding the space group in column 56 of the PDB

P1 as P 1 - all's good

P-1 as P -1 - complete nonsense although it recognizes there are two symmetry elements

P2 as P 1 2 1 - all's good

P21 as P 1 21 1 - all's good

P212121 as P 21 21 21 - no problem

But;

P21/c as P 1 21/c 1 - no recognized symmetry elements and no unit cell expansion.