ORA-01489 from all_sa_users : Why does this happen?

We very recently upgraded from 11.2.0.3 to 12.1.0.2.  We have several users where "select max_read_label from all_sa_users where user_name='myuser'" displays the max_read_label as expected, but "select * from all_sa_users where where user_name='myuser'" yields:

ERROR at line 1:

ORA-01489: result of string concatenation is too long

The users in question do not have lots and lots of OLS compartments and groups.  There are users who have many more OLS compartments and groups assigned to them for which this does NOT happen.

What could be causing this?  Any ideas appreciated!