Add to release notes

Author: onesandzeroes

doc/source/whatsnew/v0.18.1.txt

@@ -169,3 +169,4 @@ Bug Fixes
 - Bug in ``pivot_table`` when ``margins=True`` and ``dropna=True`` where nulls still contributed to margin count (:issue:`12577`)
 - Bug in ``Series.name`` when ``name`` attribute can be a hashable type (:issue:`12610`)
 - Bug in ``.describe()`` resets categorical columns information (:issue:`11558`)
+- Bug where ``loffset`` argument was not applied when calling ``resample().count()`` on a timeseries (:issue:`12725`)