how are you adding the column?
right click > edit table
i added two columns...clicked around, changed data types, added comments, etc - couldn't get the column names to reset as you describe.
Quick test :
I created a new table TABLE1 with
COL_A varchar2(20) comment aaa
COL_B varchar2(20) comment bbb
then edit TABLE1 (right click - edit table)
add COL_C varchar2(20) comment ccc
==> COLUMN1 varchar2(20) without commend added
again edit TABLE1
add COL_D number(10) comment ddd
==> COLUMN2 number(10) without commend added
(lost column name and comment but datatype was preserved)
FYI : just had a similar issue when creating a table.
( sorry for the low quality video )