Lightroom won't create new standard previews

[DavePinMinn]

Windows 11 Pro, Lightroom Classic 12.4

BEFORE I do something stupid, I'm checking here.

I VAGUELY remember getting a message from Lightroom startup a week or so ago, but I don't recall what it said.  It definitely did NOT say anything really bad like "the catalog is corrupted".  I went ahead and let Lightroom start and everything appeared, and still appears normal, so I'm not sure whatever it WAS had anything to do with what I'm getting now.

I've got several thousand images that have been imported into Lightroom over the past couple months that I'm in the process of culling.  A couple days ago, I opened one of the folders of images and only 1 preview thumbnail displayed.  All the other thumbnails were empty.  I did a synchronize to make sure there wasn't a problem, and that was fine. 

Went into Library>Previews>Build Standard Previews and it made no visible progress.  Looked at the progress bar and it had created 3 previews and was just sitting.

I tried selecting a couple folders and tried to create standard previews.  It created previews for one of the folders but not the others.

Tried again on a different folder and it created 4 or 5 or one time 7 previews, then stopped.  It just sits with NO activity.  I let it sit for about 4 hours this morning while I was gone, but there was no progress.

It doesn't SAY there's a problem, it doesn't say the previews are up to date, it doesn't crash, it just doesn't do anything.

I checked the metadata status and got everybody current.

I've shut down and restarted Lightroom a couple times with no change.

I can go into Develop and it'll build the previews but it's VERY slow.

I can tell it to build 1:1 previews for the folder and it does that.  So, things SORT-OF work, but I can't have it quickly build a set of standard previews for a folder.

I can delete the Previews file (everything gets backed up nightly), but is there anything less drastic (blowing away all the Lightroom configuration stuff at startup isn't less drastic) I can do to force Lightroom to rebuild the standard previews without having to rebuild all of them?  All the folders that AREN'T part of the incoming/being culled folders are fine and previews are normal, so it's just the dozen or so folders of new images.

[johnrellis · Accepted solution]

"I can delete the Previews file"

That's what I recommend. Right before you go to bed, exit LR, delete "<catalog> Previews.lrdata", restart LR.  Then in Library Grid view, select all photos and do Library > Previews > Build Standard-Sized Previews.  Go to sleep.

[DavePinMinn]

I had a feeling that was going to be the better long-term solution!  In the meantime I realized (which I SHOULD have a lot sooner) that I can remove a folder of images from Lightroom, then import them and it'll rebuild. But once things are stable I'll likely backup everything, then delete the previews and let Lightroom rebuild.