Odm: Only one partial reconstruction per submodel is aligned during align_submodels

How did you install OpenDroneMap? (Docker, natively, ...)?

Docker

What's your browser and operating system? (Copy/paste the output of https://www.whatismybrowser.com/)

Chrome 79 on Linux

What is the problem?

When partial reconstructions are generated, there seems to be an issue in the reconstruction alignment output.
According to the OpenSfM sources, each partial reconstruction from each submodel is thrown into a large bundle adjustment problem, then output as a set of similarity transforms which are applied to each partial reconstruction and then saved to the aligned reconstruction file.
In reality however, it seems like only one partial reconstruction is updated. I can't seem to figure out why.

What should be the expected behavior? If this is a feature request, please describe in detail the changes you think should be made to the code, citing files and lines where changes should be made, if possible.

I would expect each and every point and shot in every partial reconstruction to be modified at least at the 1e-6 magnitude, but this only seems to be true for a single partial reconstruction in each submodel. All other partial reconstructions are identical in a side-by-side comparison for each shot and point.

(As a sidenote, I'd be interested in understanding why the similarity transform is generated to create a rigid transform, rather than just applying the bundle output to the reconstruction as a whole. I would expect this to create smoother boundaries between submodels? Outlier handling?)

How can we reproduce this? (What steps did you do to trigger the problem? What parameters are you using for processing? If possible please include a copy of your dataset uploaded on Google Drive or Dropbox. Be detailed)

Trigger the align_submodels stage in OpenSfM on a dataset split into multiple submodels which also contains multiple partial reconstructions. This should be easily achievable by lowering the minimum feature count and setting a split on a dataset with a sufficient number of entries.