The % indicator is sometimes not entirely accurate with some input files, but the file is still converting.
Our suggestion is to leave the conversion running even if the % indicator keeps going up.
What happens in technical terms is that sometimes, input video files contain incorrect metadata regarding their length. Clipchamp uses this metadata to calculate the conversion progress.
If for instance the video length metadata is 5 minutes but the video is actually 10 minutes long, we would (incorrectly) show a conversion progress of 200% at some point.
This does not affect the conversion as such, which will complete eventually. If you encounter such a case, please give it a bit more time - once it is done, the finished video will appear in the "Save and share converted video" section.
We understand that this occasional behaviour may be confusing. We are currently investigating better ways to correctly estimate and report the conversion progress.