Milestone burndown chart broken after moving issues between milestones

Summary

I moved all issues from 2 closed milestones to two new milestones. Now the burndown chart in the new milestones is broken and does not reflect the data.

Steps to reproduce

1. Open two milestones, A & B.
2. Add issues over time.
3. See a working burndown chart as issues are closed over time.
4. Close the milestones after its date has expired.
5. Create two new milestones, C & D.
6. Move issues from both A & B into C and from both A & B into D.
7. Look at the burndown charts in C & D.

Example Project

That would take me several days to do, since I cannot move the clock.

What is the current bug behavior?

"-1 issues" on random dates. Chart line does not reflect the data.

What is the expected correct behavior?

Chart line reflects the data.

Relevant logs and/or screenshots

Output of checks

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Results of GitLab application Check

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Possible fixes

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