libreelec & tvheadend – recording to sd card

I installed libreelec and tvheadend on my Raspi 2. I can watch TV and use the EPG for most channels. However, I cannot record anything. In the log of tvheadend I can see an error message: Not enough disk space

The 32 GB micro SD is almost empty. I tried the default path, /dev/mmcblk0p2/storage/downloads/Recordings, andfile:///storage/downloads/Recordings

No success.

Any idea what is wrong with my setup?

Thank you.