Per the FAQ: "Xper points are calculated nightly and can take up to 24-48 hours to appear on your account.
If your Xper points do not increase after that time frame, please note that an entry you submitted might have been removed, or a question/take that you shared your opinion on might have been removed. If you want further details regarding why your Xper points were not added to your total, please contact us."
The update of the pending value is probably handled by a batch task that runs every 24 hours and updates the pending changes. I'm not sure why it's not directly altered and retrieved, though. There must be some awkward ancient legacy system managing it.