ORA-01691 (unable to extend lob segment) even though my tablespace has AUTOEXTEND on

I am getting an error:

ORA-01691: unable to extend lob segment ABC.SYS_LOB0000167347C00131$$ by 1024 in tablespace XYZ

But this is very strange to me because the tablespace has AUTOEXTEND on. What is the likely reason that this happens and how can I overcome it?

Thanks.