Approaching the Solstheim dragon mound generates the following Papyrus error:
[01/22/2020 - 07:20:31PM] error: Cannot call IsDead() on a None object, aborting function call
stack:
[ (04034ED7)].FXDragonMoundScript.OnCellLoad() - "FXDragonMoundScript.psc" Line 64
[01/22/2020 - 07:20:31PM] warning: Assigning None to a non-object variable named "::temp4"
The issue seems to be that the Solstheim dragon mound base inherited the default dragon mound script but set no properties, so the dragonRef is set to None and this causes an error.
Based on the fact that both the nearby dragon and the dragon mound dirt cap have DefaultDragonEnableMarker set as their enable parent, it appears that this mound was supposed to be set up similarly to those dragon mounds with the inherited dragon mound script removed. That is, the dragon is already present and the dirt cap disabled once DefaultDragonEnableMarker is enabled. Proposed fix is to simply remove/uninherit the script from the mound base.
Fix attached.

Attached Files:
Solstheim Dragon Mound Fix.zip