Updating project to 4.12 corrupts Additive AimOffset thumbnail, causing log spam

Updating project to 4.12 corrupts Additive AimOffset thumbnail, causing log spam

LogAnimation:Warning: Setting an additive animation (Owen_AimOffset) on an AnimSingleNodeInstance is not allowed. This will not function correctly in cooked builds!

This repeats every few seconds for as many animations are in your aimoffset

1. Open the attached project in 4.11
2. Find the Owen_AimOffset and note the thumbnail
3. Open the output log and look for log spam (not expected to find any)
4. Open the project in 4.12
5. Find the Owen_AimOffset and open it
6. Switch back to the Content Browser
7. Open the output log

Result: Log spam, see error in description. Also the Owen_AimOffset thumbnail doesn't show the character correctly.
Expected: Thumbnail is correct and no log spam

False Additive displacement of the bones