I've been trying to recreate your problem by copying what I see in your screenshots and the only way I can make the shadows disappear is either to set the light angle low so the shadows are off-screen, turn on the ambient node for the ground, setting the fly to not cast shadows, or setting the light intensity to 10000000.0%.

Out of curiosity, are you using the construct or the flat ground? I've been testing with both and it hasn't made a difference yet.

---

Available on Amazon for the Kindle E-Reader Monster of the North and The Shimmering Mage

Today I break my own personal record for the number of days for being alive.
Check out my store here or my free stuff here
I use Poser 13 and win 10