When I create an album in LR on my laptop, I come home to continue working and a small, completely random assortment of photos will be there on my iMac. For instance today I uploaded a session of 330ish photos, did some editing then came home. Open up my iMac and 23 photos are in that album from that session. Some edited, some not. In no particular order. Some from the beginning, some from the middle and a few of the last shots I got?
Well you do relalize that first they have to Upload to the Net from your laptop you were using and then they have to Download to your iMac from the net. One can't happen without the other happening. So ig you turned off or disconnected you laptop before all the images got Uploaded they certainly be downloaded to your iMac.
All of this does Not happen with the snap of your finger. Maybe someday but not now.