@vertigoeighty
That should be OK as long as the plugin actually works normally. That error is reported by VAM itself, not by the plugin. The plugin doesn't really care what morphs are being referenced in scenes or presets, it loads and uses the morphs it needs from the package regardless (and it also zeroes all TM_ and BM_ morphs from other package versions to prevent those from lingering).
Can you check what version of the plugin the morphs are actually referencing in the save file? You can open the scene or preset in a text editor and search for "Naturalis".
The latest version doesn't have all of the same morph files as before. When you load a scene/preset that references morphs from let's say the 15.var package, but don't have 15.var present in your installation, VAM will load it using the latest version that you do have installed, in this case 38.var. Since 38.var doesn't have the same morph files, VAM can't find the files that are referenced.
I tried saving a Pose Preset using 15.var and loaded it with only 38.var present... Oddly enough, I didn't get any errors even though the morphs UP Breasts Flatten L/R and UP Breast Zero L/R are definitely referenced in the preset file and are not found in 38.var. I'm also on VAM 1.22.0.3. I'm probably doing something differently...
As a side note, generally when you save a pose, it's best practice to disable the plugin first so that the morphs don't even get saved into the preset. It's annoying manual work, but unfortunately I don't currently have a way to automate that since VAM doesn't offer a way for plugins to latch onto the pose saving event.
When saving a scene however, the plugin should set all of the morphs to zero to ensure the scene file doesn't reference them. So I'm surprised that you're getting errors like this when loading a scene, that shouldn't happen at all.