BUG: dataframe.goupby()
i have a .py document work ok in before edition, but fail in 1.3.1

these two sentence fail:
   a = abc.loc[:, ['name', 'gl', 'time']]
  output = a.groupby(['name']).sum().reset_index()

it run ok before, but under  pandas edition 1.3.1, it report fail.
i found  output is not what i want , it only have one series with 'name'. the output dataframe drop 'gl' and 'time' list. 
it seems  groupby  function not work well.
so strange is ,  i found if i use  a.groupby(['name']).sum(0).reset_index(drop=False),  i add a 0 into sum(), it work well and output is ok.
so strange...


 