From the Execution Trend report, it says:
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Displays the actual test execution progress against the planned progress. This report uses weight to determine how much work is complete, how much work is left, and whether progress is being made as expected.
This is a data warehouse based report so make sure that the data collection jobs have been run successfully.
Make sure there is valid data in the test schedules of the test plan.
Make sure the TCERs are associated with the test plan and test milestone(s) in the report.
The days behind or ahead of schedule information is based on the date of the last data collection job.
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It suggests the conditions for this report. From your description, it looks to me you have made all required conditions.
If your question is why "many test plans are not listed in the options of the available test plans for 'execution trend report'.", then the conditions of this report wont matter here. If I created a new test plan without doing anything, after running data collection jobs, I will be able to see the test plan available in the Test Plan section of this report, although the result of selecting this test plan wont provide anything for this report.

So you may create a new test plan and run the etl jobs and see whether they are successful(make sure all jobs for QM are selected and executed). If the test plan is not in the TestPlan section of this report, you may want to check with qm.log and qm-etl.log and see if there is anything wrong in the logs when etl jobs were executed.