Sorry it took me so long to look into it... =|
I tested it out both in my MV and MZ debug projects, but I was unable to reproduce the behavior you describe. If I understood your issue correctly, what I did was setup an event with an idle and default poses configured, and then tested its behavior first with a random movement set, then with a custom fixed movement of just turning around and changing directions. In both cases it worked just fine, without the graphics "flashing".
However, I did experience similar issues early in development. Back then, it was due to the pose spritesheet not being loaded to memory yet. In theory, I solved that by adding a preloading system to my code. But I think it could still happen depending on how your pose spritesheets are created. For instance, if there are any blank spaces in your spritesheet, the "flashing" can just mean when the plugin switches between then it first lands in a blank sprite before changing it. For this example, you could solve this making sure there are no blank sprites in your character sheet.
I hope this is helpful... otherwise, I would need you to send me a sample project with the issue present so I could take a look =/
