NOTE: I use HL Classic, not HLO. However, since HLO is supposed to be just a porting of HL Classic into the HLO system, the following may well be accurate.
EDIT: Upon further reading, it appears Paizo did not include Ki Pool (and thus any of the Ki talents) for the Unchained Rogue. So, by RAW Unchained Rogues don't have access to them. Their inclusion in the UC Rogue talent list in HL should probably be reported as a bug. My guess is that if they fix it at all it will only be fixed in HLO.
- The Rogue Talent "Ki Pool" grants a rogue a small Ki Pool.
- In HLC, this talent appears to be available to Rogues, but not to Unchained Rogues.
- This is likely a bug, and should be reported as such both for the HLC and HLO systems - they can sort through the RAW and determine if it's working as intended or if it's a bug.