BUG: read_excel with openpyxl results in empty data frame
- [ 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.

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

-----

#### Old behavior with xlrd 1.2.0 (last version with XLSX support)

```
>>> import pandas as pd
>>> df=pd.read_excel('infile.xlsx', engine='xlrd')
<stdin>:1: FutureWarning: Your version of xlrd is 1.2.0. In xlrd >= 2.0, only the xls format is supported. As a result, the openpyxl engine will be used if it is installed and the engine argument is not specified. Install openpyxl instead.
>>> df.shape
(843, 11)
```

File is read perfectly and dataframe is ok, with all 11 columns.

#### Problem description

When using openpyxl as engine for read_excel:

```
>>> import pandas as pd
>>> df=pd.read_excel('infile.xlsx', engine='openpyxl')
>>> print(df)
Empty DataFrame
Columns: [Column1, Column2, Column3]
Index: []
>>> df.shape
(0, 3)
```

Only the 3 first headers are read, and it stops.

However, if the file is opened directly with openpyxl, it works fine, I'm using it to open and save the file with a temporary name to make openpyxl work as engine on Pandas:
```
>>> wb = load_workbook('infile.xlsx')
>>> wb.save(filename = 'temp.xlsx')
>>> pd.read_excel('temp.xlsx', engine='openpyxl')
>>> df.shape
(843, 11)
```



<details>

INSTALLED VERSIONS
------------------
commit           : 3e89b4c4b1580aa890023fc550774e63d499da25
python           : 3.8.6.final.0
python-bits      : 64
OS               : Linux
OS-release       : 4.19.128-microsoft-standard
Version          : #1 SMP Tue Jun 23 12:58:10 UTC 2020
machine          : x86_64
processor        : x86_64
byteorder        : little
LC_ALL           : None
LANG             : C.UTF-8
LOCALE           : en_US.UTF-8

pandas           : 1.2.0
numpy            : 1.19.5
pytz             : 2020.5
dateutil         : 2.8.1
pip              : 20.1.1
setuptools       : 49.3.1
Cython           : 0.29.21
pytest           : None
hypothesis       : None
sphinx           : None
blosc            : None
feather          : None
xlsxwriter       : 1.3.7
lxml.etree       : 4.6.2
html5lib         : None
pymysql          : None
psycopg2         : None
jinja2           : 2.11.2
IPython          : 7.19.0
pandas_datareader: None
bs4              : None
bottleneck       : None
fsspec           : 0.8.5
fastparquet      : None
gcsfs            : None
matplotlib       : 3.3.3
numexpr          : None
odfpy            : None
openpyxl         : 3.0.5
pandas_gbq       : None
pyarrow          : None
pyxlsb           : None
s3fs             : None
scipy            : 1.6.0
sqlalchemy       : None
tables           : None
tabulate         : 0.8.7
xarray           : None
xlrd             : 1.2.0
xlwt             : 1.3.0
numba            : None

</details>

