Last tick label not showing

[MarcoGorelli]

Noticed while working on #31207

Code Sample, a copy-pastable example if possible

from pandas import date_range, Series
import matplotlib.pyplot as plt

index = date_range("1/1/2011", periods=2, freq="H", tz='UTC')
ts = Series([188.5, 328.25], index=index)
ts.plot()
plt.show()

Problem description

Here's the output I see:

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Expected Output

Would have expected both xticks to be labelled

Output of pd.show_versions()

[paste the output of pd.show_versions() here below this line]
INSTALLED VERSIONS

commit : d448f7df88534da7c791efa3ef7eff3c72985cb3
python : 3.7.6.final.0
python-bits : 64
OS : Linux
OS-release : 4.15.0-74-generic
machine : x86_64
processor : x86_64
byteorder : little
LC_ALL : None
LANG : en_GB.UTF-8
LOCALE : en_GB.UTF-8

pandas : 0.26.0.dev0+2017.gfc813e76e
numpy : 1.17.3
pytz : 2019.3
dateutil : 2.8.1
pip : 19.3.1
setuptools : 45.0.0.post20200113
Cython : 0.29.14
pytest : 5.3.3
hypothesis : 5.1.5
sphinx : 2.3.1
blosc : None
feather : None
xlsxwriter : 1.2.7
lxml.etree : 4.4.2
html5lib : 1.0.1
pymysql : None
psycopg2 : None
jinja2 : 2.10.3
IPython : 7.11.1
pandas_datareader: None
bs4 : 4.8.2
bottleneck : 1.3.1
fastparquet : 0.3.2
gcsfs : None
lxml.etree : 4.4.2
matplotlib : 3.1.2
numexpr : 2.7.1
odfpy : None
openpyxl : 3.0.1
pandas_gbq : None
pyarrow : 0.15.1
pytables : None
pytest : 5.3.3
pyxlsb : None
s3fs : 0.4.0
scipy : 1.4.1
sqlalchemy : 1.3.12
tables : 3.6.1
tabulate : 0.8.6
xarray : 0.14.1
xlrd : 1.2.0
xlwt : 1.3.0
xlsxwriter : 1.2.7
numba : 0.47.0

[leicmi]

I can reproduce the problem with the most recent pandas- and matplotlib-version, with a very simple DataFrame:

import pandas as pd
import matplotlib.pyplot as plt

df = pd.DataFrame({"y1": {"x1": 1, "x2": 2}, "y2": {"x1": 2, "x2": 3}})
print(df)
#     y1  y2
# x1   1   2
# x2   2   3

df.plot()
plt.savefig("out.png")

Interestingly, this error does not occur with one or three data rows.

Output of `pd.show_versions()`

INSTALLED VERSIONS
------------------
commit           : ca60aab7340d9989d9428e11a51467658190bb6b
python           : 3.8.10.final.0
python-bits      : 64
OS               : Linux
OS-release       : 5.10.102.1-microsoft-standard-WSL2
Version          : #1 SMP Wed Mar 2 00:30:59 UTC 2022
machine          : x86_64
processor        : x86_64
byteorder        : little
LC_ALL           : None
LANG             : C.UTF-8
LOCALE           : en_US.UTF-8

pandas           : 1.4.4
numpy            : 1.23.3
pytz             : 2022.2.1
dateutil         : 2.8.2
setuptools       : 44.0.0
pip              : 20.0.2
Cython           : None
pytest           : None
hypothesis       : None
sphinx           : None
blosc            : None
feather          : None
xlsxwriter       : None
lxml.etree       : None
html5lib         : None
pymysql          : None
psycopg2         : None
jinja2           : None
IPython          : None
pandas_datareader: None
bs4              : None
bottleneck       : None
brotli           : None
fastparquet      : None
fsspec           : None
gcsfs            : None
markupsafe       : None
matplotlib       : 3.5.3
numba            : None
numexpr          : None
odfpy            : None
openpyxl         : None
pandas_gbq       : None
pyarrow          : None
pyreadstat       : None
pyxlsb           : None
s3fs             : None
scipy            : None
snappy           : None
sqlalchemy       : None
tables           : None
tabulate         : None
xarray           : None
xlrd             : None
xlwt             : None
zstandard        : None