Send to Printer in Cura 2.5 does not work

Hi. I use Cura 2.5 on Mac with my Robo R2. Cura is correctly connected to the printer via the API token. When printing, I can actually monitor temperature and progress (and webcam) through Cura. But when I try to send an object directly from Cura to the Printer (Send to Printer button), it does not work. Something seems to be transferred but the printer doesn't start to print the object and the file also doesn't appear in the files section of OctaPrint. I have to save to file (i.e. Desktop) and then upload/print it from within. OctaPrint myself. Did somebody already see/solve this issue?

 

It worked fine for me this summer, but I then stopped using Cura altogether so no idea on current versions.