BUG: Groupy By
- [x] I have checked that this issue has not already been reported.

- [x] I have confirmed this bug exists on the latest version of pandas.

- [x] (optional) I have confirmed this bug exists on the master branch of pandas.

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**Note**: Please read [this guide](https://matthewrocklin.com/blog/work/2018/02/28/minimal-bug-reports) detailing how to provide the necessary information for us to reproduce your bug.

#### Code Sample, a copy-pastable example

```python
# Your code here
import pandas as pd
df = pd.DataFrame([[1,2,3],[1,4,5],[2,3,4]],columns=['a','b','c'])
grouped = df.groupby('a')
print("GROUPED:")
print(grouped) #prints  pandas.core.groupby.generic.DataFrameGroupBy no frame...

grpA = grouped.apply(lambda grp: grp[:])
print('GROUPED A:')
print(grpA) #prints grouped df.

grpB = grouped.apply(lambda grp: grp)
print('GROUPED B:')
print(grpB) #doesn't print grouped df just prints the normal df.
```
#### Current Output
GROUPED:
<pandas.core.groupby.generic.DataFrameGroupBy object at 0x1205a1a90>
GROUPED A:
     a  b  c
a           
1    0  1  2  3
     1  1  4  5
2   2  2  3  4
GROUPED B:
      a  b  c
0    1  2  3
1     1  4  5
2     2  3  4
#### Problem description
Why is they print(grouped) not working ?
Also why is there different output for grpA, grpB : grpA get's nicely grouped while grbB just prints the orginal df.
shouldn't  df[:] and df   be the same as I have used in apply function , why are they producing different output?

#### Expected Output
GROUPED:
<pandas.core.groupby.generic.DataFrameGroupBy object at 0x1205a1a90>
GROUPED A:
     a  b  c
a           
1    0  1  2  3
     1  1  4  5
2   2  2  3  4
GROUPED B:
     a  b  c
a           
1    0  1  2  3
     1  1  4  5
2   2  2  3  4
#### Output of ``pd.show_versions()``

<details>

INSTALLED VERSIONS
------------------
commit           : 67a3d4241ab84419856b84fc3ebc9abcbe66c6b3
python           : 3.7.7.final.0
python-bits      : 64
OS               : Darwin
OS-release       : 20.1.0
Version          : Darwin Kernel Version 20.1.0: Sat Oct 31 00:07:11 PDT 2020; root:xnu-7195.50.7~2/RELEASE_X86_64
machine          : x86_64
processor        : i386
byteorder        : little
LC_ALL           : None
LANG             : None
LOCALE           : None.UTF-8

pandas           : 1.1.4
numpy            : 1.19.4
pytz             : 2020.4
dateutil         : 2.8.1
pip              : 19.2.3
setuptools       : 41.2.0
Cython           : None
pytest           : None
hypothesis       : None
sphinx           : None
blosc            : None
feather          : None
xlsxwriter       : None
lxml.etree       : None
html5lib         : None
pymysql          : None
psycopg2         : None
jinja2           : 2.11.2
IPython          : 7.19.0
pandas_datareader: None
bs4              : None
bottleneck       : None
fsspec           : None
fastparquet      : None
gcsfs            : None
matplotlib       : 3.3.3
numexpr          : None
odfpy            : None
openpyxl         : None
pandas_gbq       : None
pyarrow          : None
pytables         : None
pyxlsb           : None
s3fs             : None
scipy            : None
sqlalchemy       : None
tables           : None
tabulate         : None
xarray           : None
xlrd             : None
xlwt             : None
numba            : None

</details>
