Error list when exporting to .fbx

Hi folk. Ive been building a mesh for a mine to hopefully use in UE4. As far as I can see there is nothing visibly wrong with the mesh when saved as a blender file. However when I export the mesh as a .fbx file I get a window pop up with several items in it which I dont understand what they are or how to correct them. so the following is what comes up when I export. Any help would be appreciated.

Traceback (most recent call last):
File “J:\Blender 2.83\2.83\scripts\addons\io_scene_fbx_init_.py”, line 634, in execute
return export_fbx_bin.save(self, context, **keywords)
File “J:\Blender 2.83\2.83\scripts\addons\io_scene_fbx\export_fbx_bin.py”, line 3198, in save
ret = save_single(operator, context.scene, depsgraph, filepath, **kwargs_mod)
File “J:\Blender 2.83\2.83\scripts\addons\io_scene_fbx\export_fbx_bin.py”, line 3094, in save_single
fbx_objects_elements(root, scene_data)
File “J:\Blender 2.83\2.83\scripts\addons\io_scene_fbx\export_fbx_bin.py”, line 2894, in fbx_objects_elements
fbx_data_mesh_elements(objects, me_obj, scene_data, done_meshes)
File “J:\Blender 2.83\2.83\scripts\addons\io_scene_fbx\export_fbx_bin.py”, line 1174, in fbx_data_mesh_elements
elem_data_single_int32_array(lay_uv, b"UVIndex", (uv2idx[uv_id] for uv_id in _uvtuples_gen(t_luv, t_lvidx)))
File “J:\Blender 2.83\2.83\scripts\addons\io_scene_fbx\fbx_utils.py”, line 504, in elem_data_single_int32_array
return _elem_data_single(elem, name, value, “add_int32_array”)
File “J:\Blender 2.83\2.83\scripts\addons\io_scene_fbx\fbx_utils.py”, line 451, in _elem_data_single
getattr(sub_elem, func_name)(value)
File “J:\Blender 2.83\2.83\scripts\addons\io_scene_fbx\encode_bin.py”, line 161, in add_int32_array
data = array.array(data_types.ARRAY_INT32, data)
File “J:\Blender 2.83\2.83\scripts\addons\io_scene_fbx\export_fbx_bin.py”, line 1174, in
elem_data_single_int32_array(lay_uv, b"UVIndex", (uv2idx[uv_id] for uv_id in _uvtuples_gen(t_luv, t_lvidx)))
KeyError: ((nan, nan), 100)

location: :-1