Item connected to multiple projects cannot be found

I have two projects sharing the some milestones. When I do a query for the milestones I get different results.

In Project 1234 I get all milestones. In Project 5555 I only get the ones that are not included in 1234.

My Query looks like this (with some additional paramters): /api/v1/projects/1234/releases

In the web interface I can see that 1234 is listed first on that milestone.
This looks like a bug to me. Is there any way to get all releases connected to 5555 regardless of which other Projects they are also connected to?