Most Jira date fields also contain the time component. Jira doesn’t currently support convenient use of = and IN operators with timestamps. You should use the comparison operators instead: <, <=, >, >=

The following JQL keywords contain timestamps:

• attachedOnDate

• updatedOnDates

• commentedOnDate

• commentUpdatedDate 

For example, this query fails to find issues commented on a particular day:
commentedOnDate="2020/06/01"
Jira returns an empty result even if there are issues that were commented on 1 June.

The workaround is to search for the range of dates:
commentedOnDate>="2020/06/01" AND commentedOnDate<"2020/06/02"
Jira returns issues that were commented between midnight 1 June and midnight 2 June.