Hi @Audrey Yip ,
Did you clear all the filter first and then re-filter in the second Table?
How did you filter?
It's not very clearly the problem about the PivotTables, please be a bit more precise to explain your problem so that I can get more accurate solutions to this problem. I’m glad to help and follow up your reply.
I also suggest you refer to the article and check the part of Notes about Relationships:
https://support.microsoft.com/en-us/office/create-a-relationship-between-tables-in-excel-fe1b6be7-1d85-4add-a629-8a3848820be3
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