In the Traceability report, after applying filters, a maximum of 500 items can be selected.

In the Traceability report, after applying filters, more than 95,000 items are available. However, the system currently allows selecting a maximum of 500 items at a time.
To select more than 500 items, we would need to navigate through each page and clicking “select all” individually. With over 190 pages, this approach isn’t feasible.

According to the PTC team, 500 items are the maximum limit of items allowed to be selected in this table view.

Please refer below Resolution article.
Resolution Article-Is it possible to view more than 500 Work Items in the Reference Linking screen in Codebeamer<https://www.ptc.com/en/support/article/CS449187>

From the user’s perspective, Filtering returns over 95,000 items, making it impractical to navigate more than 190 pages and select them individually. The user strongly requests the ability to select all filtered results at once and wishes to have this functionality.