I find this behavior strange and annoying. Maybe I've failed to set a correct preference or something so I'm looking for help. Let me explain in detail.
OK, so I've uploaded 900 RAW pics into LR that I'm going to use for a time lapse. I import them with the "auto tone" setting applied. Then I take the first photo, make adjustments to it, select all the other photos and "click" sync. I'm in Library Module, Grid View. Those pics that are visible on my monitor start to show the changes that were applied to the first photo. However, after all the photos that are visible in the grid view show the changes I scroll down to see some of the other photos that were NOT visible. I then find that those previously invisible photos have not been changed but that they immediately start to change as soon as I scroll and they become visible.
Why does LR care what I'm looking at? It should know I've synced them all and that I want them changed asap. I don't want to have to keep scrolling to get them altered.
I'm using a PC with latest LRCC, Windows 10. But I"ve seen the same behavior on on old Mac too.
I'm pretty sure this is normal behavior. If you make Develop changes to a large number of image files (i.e. Sync across 900 images) the previews are not automatically updated. This allows you to continue working on other images without taking a performance hit while LR builds the Previews. The best suggestion I can give you is to select all images that have just been edited, and in the Library module use menu Library> Previews> Build Standard Previews (or 1:1 Previews). It will take quite some time to update 900 previews and performance inside LR will be slower until completed. This gives you the option to choose when it's convenient to rebuild the previews.
Thanks. Yes, this answer is correct. If you use the Library> Previews> Build Standard Previews method for building the previews after you have synced photos then all the photos including the hidden ones will be updated.