itunes 12.3 ist downloading podcasts as file "download.mp3"

I'm using podcast about a long time.

I listen to about 10 different podcasts.

iTunes, iphone are configured to download new podcasts and do not delete any of them

Until September it all was fine, new podcasts are downloaded to ...\iTunes Media\Podcasts

Today I noticed that (since 3 days) new podcasts are downloaded to the directory ...\iTunes Media\Downloads\Podcasts\xxxxx.tmp\download.mp3.

xxxx is the title of the new podcast

One reason is possible, I don't have enough space on my disk and moved the directory Podcasts from the directory "iTunes Media" to another disk and created a link to the new place (with junction from sysinternals). In iTunes there is no configuration for the target directory.

My songs are not controlled by iTunes. I deactivated the feature for automatically control the media folder.