Unknown export failure

Hi, I'm having a weird problem with the trial version of Voukoder Pro and Premiere Pro 26.3.0. I installed the latest version of Vokoder and and FFMpeg and set up a system variable for its folder. When I try to export with default settings, I get the following error:

I thought maybe the program couldn't find FFMpeg or my installation was missing something, so I installed the version linked here. Same problem. I uninstalled program and reinstalled it. Same thing. Then I noticed that I had an older version of Voukoder (2.0.12) that I never got a chance to test. I tried installing that instead and the default scene export worked. But when I changed it to other encoders like LiBSVTAV1 or LIBAOM-AV1, it failed with the same error. I uninstalled the old version, deleted all the Voukoder folders on C:\ and installed the latest one again: same error, even with the default scene. Changing debug to trace didn't help:

Export Error
Exporter returned bad result.
Writing with exporter: Voukoder Pro
Writing to file: I:\Premiere Projects\TEST.voukoderpro
Around timecode: 00:00:00:00
Component: Voukoder Pro of type Exporter
Selector: 9
Error code: 20

Any idea what the problem might be?

I uninstalled one before installing the other and removed both folders (in Program Files and Appdata\Local). Then did the same before reinstalling the latest version. Are there some leftover registry settings I may need to delete? As for the logs, I checked and the only things they show are my system specs (Win11, common Intel CPU and NVIDIA GPU) and this:

(info)    [VoukoderPro.cpp:201] Validating license ...
(error)    [VoukoderPro.cpp:206] Please license this product!
(debug)    [NetworkLicenseChecker.cpp:140] License responder stopped.

Since it's a trial version, I assume this is normal? There are no other log entries apart from that.

What can possibly cause PRORES_KS work in 2.0.12 but not in the latest version and cause AV1 fail in both? I thought it must have been a FFMpeg problem for sure, but my FFMpeg installation seems solid. I have C:\Program Files\FFMpeg\bin as a system variable and tried installing the binaries from both ffmpeg-8.1.2-full_build-shared from gyan.dev and the GPL build from your download page into that folder. Very weird and really annoying.

I finally figured it out. It wasn't the license but a rather silly mistake and a lot of consequent confusion on my part.

The first time it failed was because I still had leftover files from the old version, which probably broke the new version's trial license or something. But after that, the reason PRORES_KS worked and LIBSVTAV1 or LIBAOM-AV1 didn't work was because of the default muxer container. I forgot to change MOV to MATROSKA when I deleted everything and tried different installations. I'm guessing MOV still doesn't support AV1 or VP9? Whatever the reason, everything seems to be working after I switched to MATROSKA.

Just leaving it here in case anyone else encounters the same issue. You may also consider implementing a more specific error description, a log entry, or something like a red border around the Muxer node and an "incompatible container" popup on an encoder/container mismatch. Anyway, thanks for the help.