the last condition (“and all those obs from that day have times”) does not seem to be satisfied. in your examples, the nearest observations in time are other observations without locations.
There is no closing observation with a correct time and a correct location on this date. Strange you cannot add a correct timestamp to an observation in the GUI, so testing was a bit diffcult. I thought that ‘‘the nearest observations in time are other observations without locations’’ is not the real problem, but the missing of a closing observation with coordinates.\
Thanks for your time.
Adding an error message that there is no valid closing observation should be nice, but I will leave it this way, cause Kueda described it as a niche feature.