I did all that already and it didn’t work (program was closed, tried at the beginning of the file, then middle, then end, all variants).
I am almost sure it is a copy/paste from forum to the “json” file that is the culprate. I saw the ( " ) character was also different after i paste it to the json file (compared to the other encoders there).
It is not copying it as plain ASCII , because in the forum it uses rich UTF format (that is why those kind of stuff, you should post with the 
tag/BBCode, to avoid those type of encoding issues when trying to copy/paste from Forum -to-> config file).
So what i did , that solved the issue is , I copied H.264 entry from the json file itself with notepad, placed it right above H.264 entry (BTW - I notice, where you place it in the json file, is directly related where it would be placed in the UI encoding options list).
Edit it by only filling in the “values” from your post.
I also added/kept {“os”: “windows,” & “minSize”: [2,2],“} values that yours didn’t have but H.264 did.
Also I added the " ,” that was missing after the {“maxBitDepth”: 10} on your script.
I also shortened the name (I noticed to long names (behind 20 characters) could confuse TVAI - at least on Presets.
Now I am seeing it in the UI.
Here is my FFV1 “encoders.json” Entry:
(C:\ProgramData\Topaz Labs LLC\Topaz Video AI\models) - Just Copy/Paste
{
"text": "FFV1 - Lossless",
"encoder": "-c:v ffv1 -coder 0 -context 0 -g 1 -level 3 -slices 4 -slicecrc 1 -pix_fmt yuv420p",
"ext": [
"avi"
],
"transcode": "pcm_s16le",
"os": "windows",
"minSize": [2,2],
"maxSize": [8192,8192],
"maxBitDepth": 10,
"doNotScaleFullColorRange": "transcode"
},NOTE: for me personally i had to change the “yuv422p10le” (from your script) to “yuv420p” as my source content are at 4:2:0 at 8 Bit. when I left it at “yuv422p10le” , the video image was frozen after TVAI process.
Notepad
P.S. Once you edit the file and verify that it is working correctly, I suggest you backup your “encoders.json” file with the new FFV1 settings, as I am not sure when you update “Topaz Video AI” to a new version, if it will overwrite the file as part of the update process.
Especially with cases when the update contains changes to encoder(s) or encoder(s) settings.
