You need parameter name in reset_index, because Series name is same as name of one of levels of MultiIndex:

df_grouped.reset_index(name="count")

Another solution is rename Series name:

print (df_grouped.rename('count').reset_index())

   A  Amt  count
0  1   30      4
1  1   20      3
2  1   40      2
3  2   40      3
4  2   10      2

More common solution instead value_counts is aggregate size:

df_grouped1 =  dftest.groupby(['A','Amt']).size().reset_index(name="count")

print (df_grouped1)
   A  Amt  count
0  1   20      3
1  1   30      4
2  1   40      2
3  2   10      2
4  2   40      3