Given there are more than 50 trackers in your project, when you get the list of trackers using the /projects/{id}/trackers
REST API, it is no longer possible to list the trackers after 50. The pagination headers will always say the total number of trackers is 50, despite the fact that there should be more.
Probably introduced by git #tuleap/stable/345e38319c2bdaf49431c72d4df8538416893db0 (Tuleap 14.8), but I could not rebuild this version to confirm 😓