Power BI Report Builder Parameter Error

Hi,JatinV .I am glad to help you.
According to my observations and tests, your writeup does not have any problems with SQL Server databases

So I think the problem is most likely related to the database you are using, PostgreSQL.
Could you please first check the SQL query locally in the data source
by defining the variables and subsequently querying the data in SQL with the In keyword.
How to pass multiple value for a postgres function in SSRS - Microsoft Q&A
PostgreSQL: Search results

I hope my suggestions give you good ideas, if you have any more questions, please clarify in a follow-up reply.
Best Regards,
Carson Jian,
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.