possible problem in 2.79 with rotation

I have an animation where the figure stays in the center of the screen and the camera rotates around the figure. The camera is clamped to a bezier circle.

This has been working smoothly for the past 3 years. Suddenly, the bezier circle isn’t turning smoothly - it goes forward for about 80 degrees, back-tracks for 10-20 degrees, then starts going forward again. It may do this two or three times in a 360 degree rotation. Interestingly, the numbers under Z Euler Rotation continue to count up properly.

I tried clearing out and rebuilding my file existing - no change. So I built a new file under 2.79 which shows the problem. Old files opened in 2.79 work fine. It looks as if saving the file in 2.79 is what causes the problem.


testcircle.blend (471 KB)


In trying to fix the problem I managed to reset a number of things in the file, one or more of which caused the problem in the first place. The Clamp on the camera was set to Auto instead of Z.

now to fix the rest of the problems with the file.