OK.
I will try and reproduce it with the sample you uploaded in November 2022.
I won’t be able to look at this for a few days.
All good man 
Confirming thumbnail folder deletion does not cure problem.
An interesting point is when watching the thumbnails being created… i.e. in the ‘pictures folder’ populated with ‘picture icons’, KODI/OSMC working away sequentially replacing icons with thumbnails… a page of perfect thumbnails is usually produced, however if I scroll down from that page (to see other photos in the folder) and then back to it, some of the thumbnails will be now be corrupted. From that point, no amount of scrolling will change corrupted thumbnails back to good OR corrupt a good thumbnail. From trying this a few times, it’s always the same pictures which produce corrupted thumbnails.
This is also the behaviour if there are new photos in the folder, which OSMC/KODI hasn’t been asked to thumbnail before.
When a thumbnail doesn’t exist then the GUI shows the original and then cues up for a separate process to re-scale and save a thumbnail of the original. When you scroll enough for the initial image you saw to get unloaded from memory when you go back a thumbnail exist so it displays that instead. Thus, what your seeing is expected behavior, other than the messed up thumbnail generation bit. I think the former happens in software (slower) and the latter with a hardware assist which is why the two are not the same.
darwindesign.
Thank you for your reply, not sure I understand…
You’re saying ‘when there is no thumbnail, the GUI shows me the original…’? What process do you say is reducing the resolution of the image to the physical size of a thumbnail to display it to me? Surely that process produces (and displays) a thumbnail, not the ‘original image’?
I understand KODI to work more like this: https://kodi.wiki/view/Artwork/Cache
It works like what is described in that wiki other than it making it sound like it caches the thumbnail and then shows the cached version even on the first load of uncached artwork. It doesn’t wait for the artwork to be cached before displaying it the first time and it uses a different process to populate the screen faster. Basically if you enter say, a library screen where the artwork is not cached, then Kodi may cue up a large number of items with the majority of these not being visible on screen. So, instead of waiting on the caching to complete before showing what is actually visible on screen there is a separate process for the first time the art is displayed… at least that is how I understand it to work based on playing with it. You can change the resolution of cached artwork with an advancedsettings.xml file. If you set it to something stupid small you will see what I’m talking about. The very first time artwork is displayed it will look good and then every time after that it will be lacking in resolution.
darwindesign
Thank you, but not sure we’re talking about the same thing. I’m talking about the ‘pictures’ folder, and opening that folder with ‘View: Thumbnail’ chosen, (as the original poster above).
Before KODI has been asked to ‘show thumbnails’ of certain files (because they’re new or ‘automatically generate thumbnails’ was turned off in System.Settings.Media.Pictures), you’ll be presented with a page of
generic picture icons (all alike) with relevant file names below. If ‘automatically generate thumbnails’ has been turned on, I can watch as KODI iterates through the ‘new’ files, producing a thumbnail which replaces the generic icon. If I wanted to see the original picture, I would have to click on the relevant file’s icon and would be shown it full screen.
When you open an image or start a slideshow it does not use the cache. AFAIK the thumbnail system for the pictures section of Kodi is the same as everything else although I’m not sure if the cached images for pictures are kept long term or not.
Latest update appears to have solved this.
Needed to delete ‘Thumbnails’ folder to force thumbnail re-generation for previously corrupted thumbnails.
Needed to delete ‘Textures’ folder to get any kind of thumbnail generation for videos.
Threw a few ‘sad face’ reboots during thumbnail regeneration, but now appears to have settled down and no problems on new photos being thumbnailed.
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I can confirm, so far, so good. Latest update and a deletion of textures and thumbnails folder seems to be populating correct thumbnails. Thank you!!
It will take a while for all of my videos to be scraped but the few that have been done work, and usually by now there would be loads of blurred stripy thumbnails so I’m quietly confident it’s solved.
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Glad to hear this. I set a date in my diary to make sure to follow up on 01/10 and make sure this was completely solved, appreciating that it takes some time for issues to present.
Unless you are experiencing further issues, I will now mark this solved
Sam
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All working fine, 100% of videos now have thumbnails.
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