When detecting any blockstate that is read-only, meaning it depends on the environment around it to be determined, the value returns always false even if the debug menu shows it as true.

To test:

1. Create the conditions for the block types below
2. /testforblock x y z (insert following values)
3. Notice the error message returns that the state is false despite debug menu saying true

• grass snowy=true
• fence north=true
• fence_gate in_wall=true
• oak_stairs shape=outer_right
• powered_repeater locked=true

...and many others