Hi @KatNykiel,
Welcome! No apologies needed, there’s a lot to learn.
My first guess – is your structure in its primitive setting?
Ideally, to calculate a band structure you would first use SpacegroupAnalyzer like so:
from pymatgen.symmetry.analyzer import SpacegroupAnalyzer
sga = SpacegroupAnalyzer(struct)
struct = sga.get_primitive_standard_structure()
This follows the convention of Setyawan and Curtarolo.
If you do not do this, you may have misleading labels, or band folding if you use a supercell – and this can make indirect transitions look direct.
Perhaps this is something else, but this was my first thought!
Hope this helps,
Matt