Places disappearing

Question

I was a geography major in college and collect maps. I've spent quite a bit of time geo-tagging my iPhoto pictures. I recently upgraded from a 2011 13" MacBook Pro running Mavericks to a brand new 13" retina MacBook Pro with Yosemite. My original transfer (manually, not with the Migration Assistant) went very smoothly and all of my albums, books, and places were just the way I had them on my old MacBook Pro. I have a large iPhoto library with about 150,000 pictures, 3,500+ events, 1,000 folders and 7,000 albums and 150 books.
Unfortunately, with the Yosemite version of iPhoto my places are slowly disappearing from my pictures. Each time I close and open iPhoto some of the pins have disappeared from the maps. I started putting some back manually but they're disappearing faster than I can replace them. I recently discovered that, in fact, they're actually being consolidated. All 800+ pictures I have from the Los Angeles area are now all stuck under ONE pin/location simply called "Los Angeles". If I go to the "Manage My Places" screen, all of the places I added are still there but the pictures have become detached from them.
Here is the "Manage My Places" with all of the places/pins I've manually added over time near L.A.:
But here is how the Places map appears (note, I did start adding a few back manually, before there was only the one place/pin near downtown L.A.):
So, before I spend too much time manually adding all my places back, why are they disappearing or consolidating? Is that bit of location information part of the JPEG? What other parts of my JPEGs are disappearing? I still have a backup of my old MacBook Pro, so I could certainly restore my old iPhoto library. But I've just spent a month taking pictures, adding captions, adding places and it would take me about a month to get caught back up! I've done all the built-in rebuilding available and run the "scan images for location" on multiple albums/folders. But it's not restoring my places.
-Doug

Answer 1

Bump! No one? Does no one else use the "Places"? Anyone else losing all their places as they're being replaced by one, single pin? Building up all my places over the years has worked great. Now when I manually geotag a picture, by typing the name in and choosing one of the options listed, it puts the tag in a place somewhere else (usually nearby). So, the thousands and thousands of pictures I once had tagged at the Re-Bar in Seattle are now completely gone. There's 146 pictures geotagged there according to my Places map & pins. The pins are just disappearing faster than I can put them back. Every single block on this map should have two or three pins. How do I recover the places?
-Doug