What steps will reproduce the problem?
1. Join a 10 player raid.
2. Set the 10 player raid layout in Grid to Dynamic
3. Engage a boss with everyone in range.

What is the expected output? What do you see instead?
At first the units are properly grouped into tanks, ranged DPS, melee DPS and healers.
But after a few seconds or at combat start the layout always seems to fallback into the standard non dynamic layout, even though in the options it is still set to dynamic.

What version of the product are you using?
1.4.3 from Curse

Please provide any additional information below.
What am I missing? Is there a known problem that can cause this behavior?