Shape key animation not working for big meshes

Hi folks,
I’ve been trying to import a massive (~80,000 vertices) mesh from blender into unity, with a shape key animation made with shrinkwrap, but the animation won’t run inside unity.
i did some testing by making cubes with different numbers of vertices and animating them in the same way, and i found that the animation stopped working at about 25,000 vertices.
is this issue recognized and are there any workarounds? or is it just too many vertices for any software to handle?

Extra details
The project i’m working on includes animating a highly detailed 3D-scanned jaw inside unity.
I followed this video in making the animation (- YouTube)
The animation is made by introducing a basis in shape key to the start shape, adding a “Shrinkwrap” modifier and setting the end shape as “Target”, applying as a shape key and deleting the target object. then setting keyframes in the animation window’s Shape Key Editor and Action Editor (basic location keyframes at the beginning and the end).
Thanks for reading

For the curious, i reported the problem and this was the solution, quoting (Aurimas, QA Team):

Unity’s importer can not handle meshes with vertices or triangles count above 65,534. As you are trying to import a bigger mesh, Unity’s importer splits the mesh into multiple meshes, that’s where your object looses the animation information. As a workaround try pre-splitting your mesh in a 3d program and import them with your animation. If you have further question, feel free to reply to this email and this case will reopen,or submit a new bug report.