I have upgraded my system from Ubuntu 12.04 to Ubuntu Mate 16.04
Now I can no longer see previews of my graphics files in List View.
Preferences -> Preview is set correctly.
I can see the previews in Icon View but that is no use to me.
Could deleting .thumbnails before install have caused this?
I donāt remember having seen thumbnail previews in list view on Ubuntu MATE.
Now Iām wondering why that is. Iāve just checked and you do indeed get a thumbnail in Nautilus under 14.04.
When right clicking the image in caja and selecting preferences, you can also see the thumbnail.
@Wimpy, is this by design?
Edit: found this issue:
Preview icons in list view are showing just fine here on 16.04. This is not an upgraded system, but rather a fresh install. Youād think it would regenerate the thumbnails as neededā¦
The whole āfresh-installā versus āupgrade-installā issue is messed up in linux imo, but thatās jmo. Iām old-school, i donāt believe in lots of the new-agey computing thang as propagandized by many. jmo.
Not really sure what is being propagandized by whom, nor what you really mean by this comment, but OK.
Sometimes upgrading from a previous version does not produce the same results as a fresh install, for whatever reason. Not sure what it has to do with new-agey anything.
Could my problem stem from the fact that it was a fresh install onto the / partition, but on the /home partition I had deleted all . files/folders in ~ except the ones I needed:
.gtk-bookmarks
.mozilla/
.thunderbird/
.themes/
so that it was "semi-fresh"?
In any case, does anyone know what I should do to get my thumbnails back?
Which version of caja are you using?
Caja is version 1.12.7
Just for the record, I have an extremely old laptop running Mint 13 with MATE 1.6.1. No list mode previews there.
Iām thinking, like @ouroumov, MATE never had previews in list mode. So the real mystery is what @sgage has.
And over the years I use list mode, only list mode, and nothing but list mode. 
All i was saying is that i've been using linux since just prior to Canonical's introduction of Unity, and i have never yet seen an os-level upgrade-install give the same results as a fresh-install, nor have i ever attempted any upgrade-in-place operation on any linux distro that was successful. In my book what an upgrade-in-place install means is "try this then when it fails-as-expected do a fresh install". Upgrades work fine for individual components, mostly.
That tells me there are serious issues somewhere in the shifting of things, that makes it an issue. People who claim it isn't an issue, or who claim that it's okay for an unpowerd systems to start up in various states when power is appled, are simply incorrect imo.
Whatever, don't let it give you hives, it's cool, do what you want, anything else is jut nuts imo. 
Sgage is using Caja 1.12.7. I install Ubuntu MATE from the 16.04.2 iso last week, itās fully updated, but otherwise totally stock.
Before that I was using Debian Jessie, which is MATE version 1.8, and Iām pretty sure there were previews in list view of Caja there as well, though I couldnāt swear to it. So I donāt know what is going on any more than anyone else. Maybe Iām just lucky.
I installed Ubuntu MATE from the 16.04.2 iso last Wednesday, it's fully updated, but otherwise also totally stock. 64 bit version.
My caja is also 1.12.7.
Install notes:
Install Ubuntu Mate 16.04 (amd64) using /dev/sda2 as /, ignoring /dev/sda3.
(Choose "something else" in install options;
select sda2; click "change"; select ext4; select "format"; set mount point as / ;
select sda4; click "change"; select ext4; DO NOT select "format"; set mount point as /home;
Device for boot loader installation on sda1)
/dev/sda1 (type efi) as "Device for boot loader installation",
/dev/sda2 (type ext4) mount as / with format option,
/dev/sda4 (type ext4) mount as /home - *NO format option*
Chose options for 3rd party software (graphics, WiFi hardware, Flash MP3 and other media etc.)
English (UK) keyboard layout, turn on Internet;
System -> Control Centre -> Language Support -> set Regional Formats to English (United Kingdom) (instead of Spanish?!)
Maybe it's time for a bug report?
Just to be clear, in List View you would see a preview of a image file, the same way as you would in Icon View?
I ask because this is how it works on my system with the same specifications.
Icon View example:
List View example:
Yes, in List View I see a tiny little preview icon to the left of the filename, like a smaller version of what you see in Icon View.
Could you have some graphics package installed others donāt? Something Caja uses that would be like a missing dependency for this feature? It could be a library pulled in for something else, too.
The mystery continues.
No special graphics package that I can think of. This is a very simple installation, completely stock, just a handful of added packages none of which should have anything to do with this issue. I installed this particular instance just a few days ago, and I keep it updated daily.
Unless installing āaisleriotā provides the secret unlocking codeā¦
It may not be the main app but instead a dependency that comes with it. Aisleriot does include 3 additionals, for example.
Installed the following packages:
aisleriot (1:3.18.2-1ubuntu1)
guile-2.0-libs (2.0.11+1-10)
libgc1c2 (1:7.4.2-7.3ubuntu0.1)
libunistring0 (0.9.3-5.2ubuntu1)
But it didnāt start previews in list mode. Perhaps a developer can find it quickly. The mystery continues.
That would be a very nice addition. Hope @Bill_MI unravels this mystery. I would like to install what ever is causing that to happen.
I wonder how widespread this problem is - it would be nice to have more data points. Are lots of people seeing this? Just a few? Everyone but me?
OMG, I owe you all an apologyā¦ I just realized that, although I do so the icons for most files, I do not have them for graphical files (jpg, png, etc.) The directories I looked at didnāt contain such files, so I didnāt notice.
So Iām not speshul after all 