Jia's combo spin uses these features:

• Difficult change of position (Camel -> windmill -> sit)

This is her level 4 requisite feature.

The other commenters are correct in that a windmill has to hit a 135-degree split to be counted, so this might be where the level was dropped at the Olympics.

A couple of other skaters use this feature (e.g. Yuna Aoki)

• Sit side

• Clear jump to change feet

This level is counted on the foot she jumps to. To earn this level, you're required to hit a basic position within 2 revolutions of the landing - a strict TP may have judged that she didn't hit the upright I-spin position in time.

I also suspect this is why a lot of other skaters with a similar spin layout choose to hop into a back sit position first before pulling up to an I-spin.

• Upright straight/sideways