You are letting EGO correction work for you, make sure that you only use "VE tuning by statistics" where you know you have held a steady or slowly accelerating load.
Skip correcting the sites that have:
Few hits (lower left corner)
High variance (lower right corner)
Correct the sites that have many hits and and low variance :
A high variance is usually an indication of acceleration enrichment or rarely visited (highly transient) cells. These cells must be tuned manually, interpolate their value to match neighbouring cells that have more confident values. Always check the 3D view of the VE table, it will tell you if something is out of place. There are a few such places in your VE map.
VE rarely goes down with increasing pressure unless it's a turbo engine that is a victim of too much back pressure. VE is very linear. Chances are your tuning would be easier with fewer cells, it's such a simple engine.