Hello Mario,
Looking at your screenshot, I can see that you have LMTS set as your next extent size is zero.
Why you would reach this situation will be determined by your datafile distribution, freespace in each datafile and next extent required by your tables that are being updated.
Check the following note
599694 - LMTS autoallocate: Extent allocation
if you already know this, please ignore my message 
Regards,
Siddhesh