Reported on forums:

https://forum.kerbalspaceprogram.com/index.php?/topic/117090-wip17x-sstulabs-low-part-count-solutions-orbiters-landers-lifters-dev-thread-11-18-18/&do=findComment&comment=3592001

More precisely the issue is that the storage is always at is maximum(? unconfirmed?). Unsure if this was intentional.

Confirmed that the HAB parts have a 'deflationMult = 1' specified in configs. Seems that as these were intended purely for habitation, that the configured resources reflected those stored in the central core/pillar -- these would be EC, RCS fuel (on the equipped models), and life-support if patched for it.

CFG parts have 'deflationMult = 0.1' in configs, and they are properly adjusting the resources while in the editor.