I updated yesterday to 7.4 and am having problem with auto syncing profiles across a selection of images. The progress bar behaves as if it's syncing across all the images, but it doesn't actually do it. I'm wondering if this has something to do with the recent changes to how profiles are selected with one of the last updates. Any ideas?
I just did a quick test, and Auto Sync of the color profile Adobe Vivid to a selection of 16 raws worked on my LR 7.4.
Some initial troubleshooting steps:
1. Are all the selected photos raw? Many profiles only apply to raw, not JPEGs or TIFFs.
2. Which profile in particular are you attempting to sync?
3. Does it work if you use Photo > Develop Settings > Copy/Paste Settings in Library mode?
4. Can you narrow down a test case to a particular profile and just two photos? For better or worse, Adobe is unlikely to look at the bug unless you hand them a precise recipe they can use to reproduce the bug.