To get the date range we just need to know the first day of the month and the last day of the month. Then we can search from first day to last day.

The first day is easy because it is always 1, so just hard code it to 1

The last day can also be easy to get because you can just subtract 1 day from the first of next month using the Data Calculator Token (this even covers the leap years)

To get the Month, Day and Year from the current date in Workflow, check out these formatting options

https://doc.laserfiche.com/laserfiche.documentation/en-us/Default.htm#../Subsystems/ProcessAutomation/Content/Resources/Workflow/Tokens-Regex/Date-and-Time-Formatting.htm

You can use d for day, M for month, and yyyy for year

To get your starting date swap out the day with a hard coded 1

To get your ending date, increment the month by 1 unless it is 12 in which case set it to 1 and increment the year instead.

Swap out the day to 1 again but subtract 1 day using the date token calculator.

Now you can search for everything with a date in that month range.