I am new to 2.8. I have a metasurface made of three objects, each with some number of metaballs. The metaballs are animated -- the keyframes are inserted on each element's location and radius parameters.
In Blender 2.8, when I use the timeline to set the current frame or if I play the animation, the circles representing the metaballs animate normally but the metasurface itself does NOT update between frames. I have found that if I click in the Outliner on one of the metaballs' "data nodes" (I'm not sure the proper term for that; selected in the screenshots -- it's not the object but the object inside the object for the metaball-specific data... like a mesh for mesh-type objects) then the metasurface updates in the viewport. When rendering animation there is no problem. It's only when I play animation or change the current frame in the timeline that the metasurface doesn't update in the viewport. As you can see in the screenshots, "Update on Edit" is set to "Always" (not sure if that should affect animation anyway, but it's on.)
In Blender 2.79, the metasurface always updated when the current frame changed.
Edit: This is not too hard to reproduce with a single metaball using two meta-elements. Create a new metaball, and then in edit mode, add another element. At frame 1 in the timeline, use the property panel ("n" panel) to insert location and radius keyframes for both elements. At frame 50 (or whatever) in the timeline, modify the position and radius of both elements and set new keyframes. Now play back the animation and observe that the metasurface does not animate in the viewport.
Is there a new setting or something? Is this a bug?
The circles representing the metaballs have animated normally but the metasurface itself has NOT updated.