Made an initial report on December 23rd and did not receive any support other than canned responses. I lost a wyvern due to server lag and the creature falling through the map. This is what I sent originally and did not receive any help.
Was flying toward my base and was attempting to land in front of the doors. The animation showed that I had landed but my wyvern mount continued to drift forward through the ground. While this was happening I attempted to dismount to prevent my wyvern from taking fall damage, I also attempted to resume flying but was unable to achieve either. My base is located on a large plateau so the end result was that my wyvern continued to drift forward over the side of the plateau and eventually reached the ground where it took fatal fall damage. The situation occurred so quickly that I was unable to take video or screenshots. The wyvern was a 180 lighting wyvern when hatched. If any other information is needed I will be happy to provide it.