Windows will shrink/reduce to nothing while using the Mission Control feature. This applies to both the button and the three finger gesture. No other workspaces are open, and I have attempted to both restart the system and the dock, to no success. defaults read com.apple.dock only shows that showMissionControlGestureEnabled is enabled.
Unfortunately, I lost track of when this first appeared. If someone could nudge me in the right direction to diagnose the issue, I could tinker.
Best Answer
This is terrible, the issue resolved itself and I do not know what did it. My general usage and workflow did not change. No restart was done since posting this question, and I've attempted to recreate my previous usage.
Apologies to any who come across this issue expecting a satisfactory solution.