My book 18TB, missing video icons

I used my book 18TB for the first time today, to move video and jpg image folders from other small hard drives, it went well, but I accidentally unplugged it, and several video folders now won’t show a thumbnail from the video folder.
Everything else kept the original thumbnail, all files are visible in the folders, but if I open the folder to select a thumbnail, it says nothing matches my search, and shows nothing. I have tried a couple of the videos, and they seem to play fine, it took 11 hours uploading the stuff, so I don’t want to have to do it again. If I can avoid it.
I would be grateful for any help. It also effects photo folders, most but not all though. I am really not good with tech, so had some difficulty following instructions or replicating examples.

Try running CHKDSK in read-only mode (do not use the /f option). This may tell us if there are any file system inconsistencies.

Ok I did that, no problem found, it is only the folders loaded since I accidentally unplugged it, and those that were copying at the time.

Try using Icaros, it will fix the thumbnails issue

clear the cache here and activate icaros and restart explorer

if it still doesn’t work, add your drive location manually here using the Add button and then rebuild the cache/index

Ok thank you, what is Icurus?

How do I do this?

Where do I find all this? I am not tech-savvy, I don’t know what Icurus is.

.exe of Icaros should begin to download automatically. Once Downloaded, Install it

Once Installed, Launch the Program and Activate Thumbnailing and Properties, Set Cache to Dynamic

In Thumbnailing, Activate the Preset “Most Known”

About ICaros

From GitHub Description

Icaros is a collection of lightweight, high quality, Windows Shell Extensions.

Icaros can provide Windows Explorer thumbnails, for essentially any video media format supported by FFmpeg, this includes popular filetypes such as: Mkv, Flv, Avi, Mp4, Mov, Rmvb, M2ts, Ogm etc.

Besides the FFmpeg supported filetypes, Icaros also contains custom parsers, which can produce Cover Art thumbnails for Mkv, Flac, Ape, Mpc and several other filetypes.

Icaros also provides Windows Explorer properties for the following popular filetypes: Mkv, Mk3d, Mp4, Mov, Webm, Ogm, Ogg, Flv, Avi, Rm, Rmvb, Flac, Opus, Spx, Ape, Mp3, Mpc, Mka, Tak, Tta, Ofr, Wav and more.

Properties refer to the info shown for each file in Explorer, such as length, width, height, title, channels and so on.

Icaros works on Vista, Windows 7, Windows 8/8.1, Windows 10 and Windows 11.

My Description

Icaros is an Powerful shell extension for Windows which will fix majority of the issues which you have with thumbnails… and helps to make you display Custom Thumbnails for Videos, Just like yt videos

You need to download MKVmerge GUI to achieve this, I use an older version of MKVmerge v7.8.0 RiverMan because i simply love the older design on my Windows 8.1 more than the newer QT Based design.

Launch MKVmerge

Either drag the video into the program or add the video manually using the add button

Switch to attachments tab and add the Picture which you want to set as Video Thumbnail by clicking the add button

Once added, Click Start Muxing button and the output file will have the custom thumbnail shown properly.

Without Icaros, this change wont be seen most of the times… So you need both MKVmerge and ICaros to Beautify the File Explorer experience for videos based Folders.