I am bumping this thread because I have just found an issue in the packaging of the LensFun DB in the AppImage case. The issue was also present in the RT AppImage, and discussed here: Profiled Lens Correction is missing my camera/lens - #7 by hholt
The consequence was that the AppImage was bundling the lensfun DB shipped with the lensfun sources, and therefore quite outdated/incomplete, instead of the one provided by lensfun-update-data.
Now the up-to-date DB should be correctly bundled. Please let me know if you still encounter any LensFun-related issues…