What date field are you using in the filter? The trend report's Options tab allows you to limit the rows in the output of the report, but is not intended to filter issues included in the report. So there is no filter date that is equivalent to the date range on the trend report's Options tab. Here is an example of the two date locations.
Option #1: You create a filter for Date Created in the range of 2/20/2018 through 5/20/2018 and then use that filter in the trend report. This limits the report contents to issues created in that three month period, but the rows in the report will be open ended (ex: 1/1/1900 through 1/1/2100 depending on the contents of your data).
Option #2: You use no filter in the trend report, but specify a report option of 2/20/2018 through 5/20/2018. This will include all issues in the report, but will limit the rows in the report output to a three month period.