You are quite right, apologies. When set to zero, the height should auto adjust on mobile. That is less than desirable behaviour. I will take a look at that when I have time. I will also consider splitting that out to a mobile pair.
In the meantime, can I recommend you activate ‘tiles’ on mobile OR modify the thumbnail with a max-height, e.g.
I actually tried setting this just now and couldn’t get the fallback image to show.
I’ve set topic list default thumbnail and checked topic list default thumbnail fallback. I’ve also tried setting Image URL for thumbnail shown if topic in this category has no preview thumbnail set in individual categories and can’t get anything to display.
I’m assuming I shouldn’t need to rebake posts for this to work right?
Away from home office at mo but will double check when I get chance.
Are you getting a JavaScript error on console? Can you please make sure the linked image is hosted on (ie uploaded to) your site and retry as required?
I’ve found another to reproduce the sorting bug I previously mentioned. Go to this category, it correctly sorts by created date, visit one of the topics, click the same category link and now it sorts by latest. This happens with Tiles and Thumbnails but it does not happen without the theme component (just core)
I would not recommend installing both, you will end up with some weird behaviour. You should pick either the Topic List Previews plugin (this topic), or the theme components you linked.
Thank you. It just seems to me that if this plugin can do what the above 2 theme components can do, plus also have some other features (topic list action and ability to adjust thumbnail width/height), then I wouldn’t be losing anything by installing those theme components but only gaining.
David is quite right. The two have slightly different feature sets/look and feel. Which you install is at your discretion but are unlikely to work together. Try them both. You can switch between them if you install both TCs quite easily (TLP has a TC flavour too)
I’ve tried both and one can achieve the same results. However, I do like that this plugin offers a default thumbnail picture. I did actually use that by putting an imgur link for a category. It didn’t work. Here is the category: https://forum.duelistsunite.org/c/yugioh/strategy/13
When we upload images for category icons and headers, where are they stored? I’ll put the images in the same location but just wondering since that should be also local. I think category icons should be used as default when a default image is not given.
Can you give me an example of what I should be typing as the path for local files? I created a folder called ‘pics’ in my discourse folder. So it’s var/www/discourse/pics/image.png. Should I be putting “pics/image.png” ?
I believe James Cook’s post above had the same issue and it wasn’t solved: Topic List Previews
You should have a topic on your forum called Assets for Site Design, you just upload the image in this topic and right click on the image and copy image address
Just an update. I uninstalled the plugin and installed the theme component version of this: Topic List Previews
Using the exact same url as above (/uploads/default/original/1X/c1808d114892ff27d1a7f08e7a95c991390cb689.png) , the default thumbnail worked.
Hence, the theme component works but not the plugin. I would rather use the plugin since I can specify a different default thumbnail for each category. Also, the theme is experimental.
Most likely, I will revert to the other two theme components if the plugin can’t work for the image url.
and even Tiles view on the Suggested list on Topics. 
. It must have been an outstanding issue since Discourse core took over thumbnailing.