Could you try dragging and dropping the archive files for these shimeji on the page at the link below and see if they work as expected? (Wait for the Default Mascot to automatically spawn before trying to drag and drop your own files. It might take a few seconds the first time you open the page. If it doesn't spawn after a few seconds, that may be a different bug)
https://pixelomer.github.io/Shijima-Web/
If they work, then this issue is because Shijima-Qt has not been updated in a long while (it is missing almost a year of fixes and improvements in libshijima and libshimejifinder)... Shijima-Qt is in need of a rewrite and I haven't had the time to rewrite it yet. It'll be updated eventually.
If they don't work, then this may be a compatibility issue that needs to be resolved or an issue in Shijima-Web. In that case, could you share the links for these shimeji?