IEEE-PoE devices (PSE or PD) require a compatible counterpart. They do not regularly work with "passive" devices. There may be occasion when some combinations work but this can't be taken for granted.
The difference on the PD/splitter side is whether it has an MDI signature that tells the PSE to turn on the power. If it doesn't in your case just swap the splitter for an IEEE-compatible one.
Even IEEE-compatible splitters don't require much electronics and you could call them "passive". Essentially, they require magnetics with middle contacts and a signature resistor. Most also sport a PSU for converting down the 48-54 V from PSE to e.g. 5 or 12 V.
Generally, it's a bad idea to mix IEEE-PoE with non-standard devices. The latter can really break things.