Work Item Form Group Height not setting to 100%

I am writing an extension that is extending the work item form, and adding a work item form group. I have a manifest contribution using the ms.vss-work-web.work-item-form-group type.

According to the documentation, if the "height" property is not specified, it will set the height to 100%. However that is not happening.

When I don't specify the height property for the contribution, it is clearly setting the height to "150px" upon inspection:

This is preventing me from setting auto grow related css styles so the height will dynamically adjust depending on the content rendered within the group/frame. I can see the height being inherited in the iframe level from the .external-content-iframe class is 100%. But that is only allowing the space to fill up to the 150px height set at the higher level (in above screenshot).

If I manually set the height on the contribution manifest, I can see the height property is set in a style tag at both the vss-contentHost div level and the iframe level:

So when the "height": property is omitted from the contribution manifest, perhaps it is only setting the height to 100% at the iframe level and not the parent vss-contentHost div level.

Start by reproducing the work item form group with the height property omitted, using the linked documentation as the expected behavior. Inspect the contribution rendering around the vss-contentHost parent and external-content-iframe, then compare both computed heights with a manifest that sets height explicitly. Done means the documented sizing behavior is consistent at both levels or the discrepancy is clearly documented.