While trying to debug a program I am kicking off a "child" session using SQL window and trying to look at the data.
unfortunately, as i have to deal with the table of more then 60 columns i am getting ORA - 6558 buffer in dbms_pipe is full.
Now - that is of course not PL/SQL error. However, when i decrease amount of columns to about 10 I get ora - 6502.
Can you please look into that 6502 ?

(it appears that your grid misreading statement for the datatypes)

To obtain some more diagnostic information, can you modify the shortcut and add the DebugSQL parameter? For example:

"C:\Program Files\PLSQL Developer\plsqldev.exe" DebugSQL

Reproduce the problem and send me the debug.txt file that is generated in the PL/SQL Developer directory or in the %APPDATA%\PLSQL Developer directory (e.g. C:\Users\<User>\AppData\Roaming\PLSQL Developer).