plinkie Suggested right. In 8-direction there's no disabling of solid collusion. It can be disabled only if 8-direction disabled. Also in case of manual movement like "Move at Angle", "Sprite.X+10" collusion won't work.
When dealing with collusion and having some issues always recheck:
*Make sure Solid "enabled"
*Make sure collusion with Solid objects enabled in Behavior you use for moving object
*Check collision polygons (in left-bottom of image editor) both of moving object and solid. It may be not be the reason of objects not colliding, but often reason of incorrect collusion. So don't forget always to check this one if something wrong.
Also making moving object to rotate towards mouse if that's the one that should collide with solid is not a good solution.
It's better to use invisible object for collusion with solid and visible object for everything else set to be in same position as invisible one.