topic Screwy timeline bug messing with transforms in Fusion Support Forum

Screwy timeline bug messing with transforms

minimapletinytools — Thu, 25 Dec 2025 20:50:06 GMT

I'm working on a python library that generates fusion 360 designs for carpentry joints. When trying to scrub the timeline, I noticed the resultant model changes after go back in time and come forward. Actually it seems a transform is applied or not applied after I first go back in time and never gets applied again afterwards. I know fusion 360 has some weird script time related behaviors, but I'm surprised as this error is reproducible in after I save and reopen the f3d.

There's actually a lot of weird stuff that can happen and I have no idea what's going on. Anyways, here are screenshots of the issue as well as the f3d of the model generated by my script which does reproduce the issue.

This is definitely making it a lot harder to debug my script. There is a local/global coordinate space related bug somewhere in there and I was really wanting to rely on the timeline to find the issue :P.

Re: Screwy timeline bug messing with transforms

minimapletinytools — Thu, 25 Dec 2025 20:50:52 GMT

Just replying because I forgot to subscribe to my own topic.

Re: Screwy timeline bug messing with transforms

jeff_strater — Fri, 26 Dec 2025 17:00:24 GMT

The issue here is that you have a "upcaptured component position". You can tell this by the existence of this UI in the toolbar:

This means that a component has been moved, but the new position has not been captured. I can go into the reasons why it is implemented this way if you are really interested, but the thing to know is: This is not a bug, it is intentional behavior. If you want this component position to be permanent, you should do a "Capture Position" from this UI:

This will create a new timeline feature that does pretty much what its name implies.

That said, this is not the best way to position components. It works as long as the geometry of the component does not change. I would recommend using a Rigid Joint that references geometry and parameters in the design to assure that components will be positioned correctly if the geometry changes, and will stay in place

Re: Screwy timeline bug messing with transforms

minimapletinytools — Wed, 31 Dec 2025 15:30:17 GMT

Thanks for the response and explanation!

I did notice it gives warnings on uncaptured positions when I was doing some operations. But notably no such warnings when scrubbing the timeline which does seem to lose this state. The inconsistency had me thinking the issue I was seeing was unrelated to the uncaptured positions. Maybe there should also be warnings for uncaptured positions when rolling back in the timeline? It's also a little weird this state can be serialized without warnings.

Just feedback in case it's useful! My feedback here being based only on my one rather idiosynchratic use case.