Last night I found a floating rock on Aanthrim region. Head East out of Dondril not to far [a short distance stop at the first pair of rocks on your right then turn south looking towards the small ruins on a hill]. There is a giant stone and tree here between where you are and the ruins. Just next to this tree is a small rock that is quite high up in the air you will have a job spotting it in the construction set as it is in the canopy of the tree. It needs placing on the ground or removing. Also I have seen that there are also a few up the hill to the left of the first one. All have the same problem and are difficult to spot in the construction set.

I am using 21.01 with the hotfix patch but have identified through the construction set that this is an error within the 21.01 file..The link I gave for the co-ordinates is the first rock. The other rocks are listed bellow (I may have swapped the id between the three bellow as I took the locations in the construction set but realised I needed the names and took them from the game. My screenshot appears different to the default as I have used a tree replacer. I have verified that no other mods have done this as I have used the construction set with only the core TR_Mainland.esm and Tamriel_Data.esm after the Bethesda esm files. I have also confirmed it is not resolved in the hot fix.

Aanthirin Region  10, -22

Other rocks

terrain_rock_ai_01
x 87107.492
y -176685.641
z  3533.630

terrain_rock_ai_09
x 86541.633
y -175759.781
z 3254.854

terrain_rock_ai_03
x 86294.984
y -175876.547
z 3093.243