Items behave oddly around dirt paths when a block is placed inside of them

If a one block hole is surrounded on all sides by grass path blocks (likely to also affect blocks like farmland and soul sand), items exist in that hole, and a full solid cube block is placed into them, weird behaviour can be observed. Expected would be that the items would be ejected upwards like with full blocks, but this is not the case. The items appear to stay down there, but can still be picked up from above if the expected area is walked directly above.