Did a bunch of reading, and this thread looks very promising...

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winhelponline.com/blog/webp-appear-dark-windows-photo-viewer/

Just follow the procedure on the...

OK, thanks for the info.
I've now got it working, but I'm wondering if you see the same behavior that I do viewing webp images on Photo Viewer: the image initially loads correctly, then becomes...

Shawn,
thanks for all the work you put into this tutorial.
From what I can see in the registry mod, there isn't explicit support for webp files, which are supposed to be supported in Photo Viewer...

For those who want to fix broken filters like this, the article below provides the basic principles and the specific keys to make it all work in the registry.
...

When I looked in the file type filter selector, there were maybe 10 of the content filters indicating "registered iFilter not found"...which is certainly an indicator of trouble. Those were all for...

How/when did I notice: I keep a process counter up at all times, and normally Win10 wants to be running around 200 of them. One day, I noticed I had 2400 processes so I began to investigate. This...

Just ran in cleanboot for about 10 minutes, and the search filter task put itself into suspend mode.

So, at least we have the data there...

winver = 1803, build 17134.112 with all the patches installed.

You mention "content indexing" --what is that?
The only other thing that does any indexing is my mail tool, and that touches only...

Thanks for the ideas, Dalchina.
The index troubleshooter says everything is OK.
I have a lot of files to index, and every time I change interesting things to test the problem, the index resets...

Am running Win10pro 64bit, using windows encrypted file system and standard indexing service.

Everything had been running normally, but for some reason Windows is now throwing the Search Filter...