Test Coverage not able to pick more test links

Description
When linking more than 3048 tests to a requirement, the test coverage stops picking up the new links. 

Pre-conditions

Have a requirement with 3048 tests linked

How to reproduce

1. Open the requirement
2. Add an existing test via the Test Coverage "Add Tests" button

Actual result/Attachments

The link is created and the test shows on test coverage. If we reload the page the added test is gone.

Expected result

Linking is created and the test remains on the test coverage of the requirement