P: (Windows) Panel is limited to 1600 items (folders, keywords, etc)

If that's the case, then why does it work most of the time?  This does not appear to be a hard limit.  Like I mentioned in my original post, after messing with resolution and scaling the folders are back.

The workaround to this long-standing bug is to introduce more hierarchy into your folder structure and keep most of the parent folders collapsed.

The underlying limitation is on the size of the low-level operating system window, so as you increase the actual font size, fewer lines of text can fit into the window.

I've run into something a few times with Lightroom (both older versions and now the latest version, Lightroom Classic CC 8.0) in which at times the folder list in the Library module cuts off and does not display the bottom folders.  When that happens, the scroll bar is present but the folder list ends prematurely, often with dozens of folders missing at the bottom.  That complicates things because my naming convention for photo shoots involves folder names that start with the date, so my latest shoots are always at the bottom.  The solution has been to restart Lightroom -- and if that doesn't work, to reboot the computer.  Eventually the folder view is complete again... until the next time.

I thought the issue might be an odd quirk localized to my computer but it happened again today as I'm migrating to a brand new computer.  Brand new install of Lightroom Classic 8.0 on a clean install of Windows 10 Pro, with my catalog transferred over.  I fired up Lightroom and right off the bat the folder view was cut off with a few dozen folders missing from the bottom of the list.  I restarted Lightroom several times, rebooted the computer several times, but the missing folders remained missing.

Over the last few months I developed a hunch that this issue is related to screen resolutions (I have a 4K laptop with two larger external monitors) so I tried changing the screen resolutions and scaling settings in Windows and... after trying several options I got the folder list to be complete again.


It seems to me that there's a bug in Lightroom that doesn't always account for resolution and scaling settings.  Anyone else run into this problem?  I know I can filter the folder view for a specific folder name (which I didn't think to try when folders were missing), but I'm hoping this bug gets identified and resolved.

Every Windows application with large scrolling lists  has to cope with the maximum size that Windows imposes on low-level windows (32K pixels) by repainting the windows as necessary. Most applications do that by using commonly available libraries of user-interface controls that do the work for them.

But Adobe took a shortcut when they implemented LR Windows, choosing to implement their own controls but failing to complete the work. They did it for Library grid view but not Folders, Collections, Keyword List, and other panels. And they've never owned up to taking that shortcut.  See here for details: 
https://feedback.photoshop.com/photoshop_family/topics/bug-that-causes-collections-and-publish-servi...

We supply a patient photographing system and use Lightroom as the DAM. The majority of our clients on Windows hit the list limit for folders as each tethered session creates a new folder. We have a system for splitting into hierarchy through a plugin but it is inconvenient and it would be great if Adobe could fix this.

Thanks for merging my thread in here. When I collapse some of my hierarchies as suggested, that allows me to work around the problem for now. Hopefully, Adobe addresses the problem at some point.

I've spent a lot of time adding keywords to my photos. Well over 200000 photos. Probably several thousand hierarchical keywords. When I look at my list of keywords in the keyword panel, the list is truncate -- that is, I see about 90% of them, but near the end, the keywords stop showing and I can't scroll any further. I know the keywords are still there, because I can use them in searches. I just can't see or select them any longer. This was not a problem in Lightroom 5.

It's true that a low-level Windows control can have maximum height and width of 2^15-1 pixels. But nothing stops an application from coding its own scrolling controls, using a low-level window whose height is less than the screen height (or using a library that has done this). Any Windows application that has to display a very large list has to do this (and most do). For example, Windows File Explorer can display lists of files that exceed 32K pixels. Even LR does so for Library grid view, which can far exceed 32K pixels in height.

That is my understanding as well, John.

" There's nothing inherent in Windows that imposes such a limitation. "

I understood that the problem is because Windows has (had?) an approx 32000 pixel limit on the size of a single control, and that Adobe haven't coded the UI to work around it.