the upload inside a thread does not work if the language is de (german). If you switch back to english the upload works fine.
The Bug:
Instead of the image it only appears a text XYZ.png wird hochgeladen… instead of the image.
The locales seems correct to me:
German: {{filename}} wird hochgeladen…
English: Uploading {{filename}}…
Maybe one have to switch the order from {{filename}} wird hochgeladen… to Wird hochgeladen: {{filename}} because of a possible syntax issue (maybe it’s expecting the variable {{filename}} at the beginning)…?