It's driving me batty

I have a file with a single character. I ported everything to 2.8x using Evee.
In the viewport - the animation looks fine.
When I render the same frames - everything falls apart.

So far - I’ve rebuilt the file, redone the animation frames, tried 2.82, 2.80, and 2.81a, I’ve reset most of the settings I can find that might control the animation (I’ve probably missed something) and I still have the same problem. It makes no sense to me - it looks like the camera isn’t recording at the same rate as the animation.

It looks like your hardware isn’t fast enough to display the animation in real time. Or should the animation run so slowly and jerkily? I’m not sure I understand you correctly. EEVEE is very fast, but the classic method for evaluating speed is the Open GL renderer under View> Viewport Render Animation. You can of course adjust the frame rate in the render settings, but there are also options for setting the real-time calculation, e.g. omit frames. But more about that here:
Sync Mode !?!?

When I go to View, Viewport Render Animation, the animation plays smoothly & the arms go where they’re supposed to.
When I go do Render, Render Animation (Ctrl+F12) the arms go in strange directions & the rib cage distorts.

Another figure (less complex) renders fine,

My system has a quad-core Xeon 3.7GHz turbo processor, 16 GB of RAM, with an Nvidia GEForce 950 with 2GB of RAM.

They are both renderings, so they have nothing to do with the real time performance. Have you checked these settings: 2.80.16 for me they work properly.
Otherwise you should ask here:

this sounds strange mabe you reset the default settings: File > Defaults > Load Factory Settings and open the file without loading the user interface.

HI,it looks like as swell as mismatch of fps or timeline frames, you have major problems with the rigging itself. But without seen the file it’s going to be a guessing game.

Using 2.82 I tried resetting the Time Remapping / New to 200 (from default 100), The figure didn’t bend forward as far and the left arm still went into the rib cage. My usual settings are:

I also tried resetting to Factory Settings and opening the file without the User Interface, The render still did strange things.

The rig is “odd” but has worked fairly well for the last 5 years. I lost some “features” I’d been using with the upgrade to 2.8 (2.7 etc. let me move unconnected bones in the rig. New version has gotten rid of that.)

The problem is that the finished render doesn’t record the same motion as the Viewport render UNLESS I do it one frame at a time - which is just tedious.

Have you already tried to import the object via File> Append. Usually it works better between versions.

Yes, I did that too. It didn’t make a difference.

I’ve also deleted & recreated the animation, updated all the drivers on the rig. I’m missing something - I just don’t know what.

If you ever figure this out, PLEASE update us. It’s quite a mystery.

Well… Last night I checked the bug reports. I noticed 2 reports that might be applicable. This morning I filed a report citing the one that seemed most likely. The response was quick.

T74390 references a problem with multiple layers of constraints on a bone. All the constraints confuse things. Another reporter said their figure looked fine in the Viewport but didn’t move at all when the animation was rendered to image files.

Apparently, earlier versions of Blender ignored/handled the errors. When the code was cleaned up for 2.8, the problems started making themselves known.

So… I removed some constraints in the bones along the skeleton’s spine & magic! It works.

:worried: :worried: :worried: