What you describe in Configuration 4 does appear to be a bug sorry, I have managed to reproduce it but can't really upload a fix until the jam rating period is over now.
From what I can tell it occurs if movement and displacement occur on the same frame, which can be caused by spamming inputs.
The explaination's in the edits are pretty much correct, although that's not how I really conceptualise the first point when thinking about it personally.
I will probably write up a postmortem at some point explaining the mechanic and its inspirations in a bit more depth.
Thanks for the feedback!