I uploaded an image using url https://commons.wikimedia.org/wiki/special:uploadWizard?campaign=wlm-at&fields%5B%5D=32171&fields%5B%5D=47.70159/15.79294&captionlang=de&caption=Sog.+Huthaus%2C+Glockenhaus+am+Knappenberg+%28BDA-HERIS-ID%3A+34175%29%2C+Kleinau+23%2C+Reichenau+an+der+Rax&descriptionlang=de&description=Sog.+Huthaus%2C+Glockenhaus+am+Knappenberg&categories=Huthaus%2C+Glockenhaus+am+Knappenberg%2C+Reichenau+an+der+Rax, which contains parameters captionlang and caption.
The result of upload is https://commons.wikimedia.org/wiki/File:Huthaus,_Glockenhaus_am_Knappenberg.jpg, where SDC is missing. This worked well before.
Was there an interface change?
See https://commons.wikimedia.org/wiki/Commons:File_captions & https://commons.wikimedia.org/wiki/Commons:Upload_Wizard/Fields_prefilling