Start By Testing the disparate systems like the messaging system and then testing the other systems
This includes the rules system ,
The renderering system.
etc
The collisions system currently decides not to move any blocks if the chain contains stop.
This causes this issue where you cannot touch tiles that normally you could walk on if collision was correct.
Possible Fixes
Separate Flag Responsibility,
A Strict Collide Flag
canCollide flag
and a touch flag.
The touch flag could allow a entity to move onto it if it is the first of its kind
The canCollide flag could indicate blocks that you can bump into and interact with.
The Strict Collide Flag Could indicate anything with a canCollide Flag Should also stop you.