Map location does not always move with timeline location


This issue seems to be more problematic on Chrome than Firefox, but sometimes, when moving from a location on the timeline, the map location does not shift.
For example:

When moving from
309-311 Mechanic St., Camden, NJ
919 S. 9th St., Camden, NJ

the map location and label does not shift. I checked the coordinates in my Google Spreadsheet and they appear to be accurate.


Hm. It seems that the main problem with map labels and timeline labels not matching up happens on the first item on the timeline. The first and second items on the Harlem timeline are the same which masked the problem. When going from June 1980 Vyse Ave. at East 178th St., South Bronx, NY to 1980
Prospect Ave. at E. 149th St., South Bronx, NY the location point/label does not move to the 0 point. Should I start the timeline at the #1 point instead? If so, how would I do that? Thanks–narrowing it down.