Missing institution, report type, and report number

[pohlm01]

When I cite an IETF RFC such as RFC 6487, I expect the institution, report type, and report number to be included in the citation.
The below image shows the difference between the generated and expected results in a minimal reproducible example.

First, I suspected the ieee.csl to miss this information, but to me, it looks like the CSL correctly includes them. Neither the .bib nor the hayagriva format seem to help.

This issue might (or might not) related to #112