"With Lightroom closed go to /Users/Library/Caches/Adobe/Lightroom/Sync Data/(MAC) OR C:\Users\Username\AppData\Local\Adobe\Lightroom\Caches\Sync Data (Windows) and remove (or rename) the Sync.lrdata folder. Restart Lr and it should try to reconcile your local synced data and the cloud synced data. This can take a while depending on your machine, network connection, and the number of synced images. Additionally, when it completes it may leave some images in the All Sync Errors collection. These are usually fixable by applying any setting that forces a sync (like an exposure increase), letting it sync, and then reversing it."
Thanks for the reply. To clarify, the synchronization is with local folders on the PC and not with the Cloud.
The Sync.lrdata folder does not exist in the location you specified.
A number of people have experienced this bug, as reported in the official Adobe feedback forum: Lightroom CC 2015.2 synchronize folder does not import new images unless show import dialog is active. Please add your vote and details about your issue to that topic, to make it a little more likely Adobe will prioritize a fix soon.
With the latest update (6.2.1) I no longer have the option to sync with Lr mobile when starting a new collection. These updates are so frustrating.
With the latest update (6.2.1) I no longer have the option to sync with Lr mobile when starting a new collection.
This is a different issue than the one reported in this thread. Please post a new message with details about your issue.
As it happens I've found a workaround.
Using my example above, if I create a folder within 2015_Event_Folder (using LR) called the same name as the sub-folder on disk containing the photographs, i.e "John_pics".
If I then synchronize this folder rather than top level, the synchronization works. Photographs are added as expected, regardless of RAW, JPEG etc...