Sometimes the Lumi H5P Desktop Editor cannot open H5P files or fails to save them.
I know about this issue. It is tracked on GitHub: https://github.com/Lumieducation/Lumi/issues/2635
and our issue tracking system: https://lumi-education.canny.io/bug-report/p/editor-corrupts-files-while-saving
The reason is that the Lumi H5P Desktop Editor somehow corrupts the file while saving. I have tried to investigate this issue, but it is very complex and VERY time-consuming as it is difficult to reproduce the error.
Lumi is mostly a hobby project that I do in my free time besides being a teacher and having two kids. The Lumi H5P Desktop Editor is open-source and completely free and at the moment I am unable to work on it due to time limitations. I hope to gather enough funding soon to work on this problem, but currently, I am unable to provide a solution or help with this issue.