I seriously doubt it, but can you elaboratee on that?
Well, like with other things such as textures or materials animation actions get deleted on closing the file if they have no user. A user is not the user operating blender but an object or a mesh.
For example if you create a shader and remove it from all objects it will be gone the next time you open this scene.
You can read about fake users and actions in the manual under âWorking with Actionsâ
https://docs.blender.org/manual/en/2.90/animation/actions.html?highlight=fake%20user
If itâs corruption, why do things keep reappearing? If itâs user error, what is the point of thee feature that has data jump in and out of existence? I tried to make it seem meaningful, but itâs not. And the title is a bit bombastic, but any animator I ever knew would discard software that did this, in a heartbeat!
It could also be a problem like a dependency loop or some similar error with the rig.
Open the system console and play the animaton in viewport to see if errors or warnings are reported.
Hello again 
This does seem to be an exceptionally bad case, yes. But bad is badâŚ
No referencees, eeverything is local. And yes, linkedobjects would explain a lot, but since theyâre not linked⌠evil gnomes, maybe? I dunnoâŚ
If it just disappeared, yes. But why would it reappear while scrubbing the timeline? I think it gts dropped during some realtime updating glitch or somethingâŚ
Backup is love, backup is life. But the problem shows up long after it starts. I.e. thee backups have it, too, it just hides until suddenly⌠surprise!
Agree, but I seem to need it for this and future projects related to itâŚ
Maybe. Just⌠how??
If it reappears it really sounds a lot like a broken rig. Dependency loops in contraints or drivers or something like that.
Yeah, but the data is not deleted. It disappears and rappears while I work on the scene.
Not like that. The data is there, then it isnât, then it is again. Like if THESE WORDS just went away, then reappeared whn you scroll through the textâŚ
Yes, that happens with dependency loops. The animation looks good when playing it back and broken when rendering. The next time you play it in viewport it might not work or only partially work. then the third time you play it it might look good again.
Then you render again and half of the frames look good and half of them are broken.
I think this is happens when the rig is ambiguous. Blender does not know what to do and choses one of the possibilities and so it sometimes looks correct but sometimes it does not.
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I didnât explain that well, sorry. Things change while I simply scrub the timeline. A dependency loop creates a problem that stays there. When I look at something, it changes back and forth without anything happening. Dependency loops create a problem, yes, but that problem doesnât disappear and reappear just because you look at it, it stays the same. This does not.
I think I might need to make a whole video to demonstrate this. But hey, who has plans to do anything else, eh⌠
Edit: Iâm gtting more and more convinced that itâs some kind of bug between regular animation and NLA animation. So, not quite the loops, but in the ballparkâŚ
Not necessarily. Iâve had dependency loops that do what you discribe. They appear and disappear seemingly randomly.
Have you checked the console for errors?
I never had a loop act like that. But I should comb through the console, yes. The way the bug shows up, it seems like something that would not be noted in the console, but I should at least chek. Right now it is rendering, just to see how bad it is after some fixes, but after thatâŚ
Reading through this thread, it appears to me that if this critical issue became a thing since 2.80, and was a common occurrence to boot, then we shouldâve gotten an earful from many other users beginning in Fall of last year. If this issue is as bad as you say it is, then why has it not come up until just now?
Not to dismiss the fact that losing work can be a major setback, but the Blender userbase these days has a tendency to be very good in exposing every major issue almost right away, and with certainty would not have failed to notice such a breaking issue for an entire year.
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That being said, I do think Blender should be somewhat more proactive with alerting users to dependency loops. Putting this vital information in a console window where you will never find it unless you look for it is probably not the brightest idea. Itâs not even the python console, but the system console, lol.
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I have been using blender professionally for 15 years, every day, to produce animations, and I have never had this problem.
Maybe the problem does not come from blender âŚ
Itâs an old issue, I had it before in earlier versions. Itâs not a 2.8x issue.
And I never had a break-in or been in a car crash. Doesnât mean I insinuate my neighbours only have themselves to blame when it happens to them, so please refrain from that approach, itâs kinda hurtful. There is a highly problmatic bug in the software, and it has been there for a long time, only showing up under rare conditions (apparently). But good that it hasnât affected you. It has, sadly, affected me.
This âraising awareness for a nasty bugâ thing is not helpful. Too many generalisations, lack of vital informations.
It would help if you get active and create Blend files which reproduce the problem.
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It is obvious that it does not affect everyone, do not see much people here confirming it. Is this bug reported previously?
You seem to be mostly interested in making scandalous car analogies, but Iâll try : a bug, big or not big, is a bug. If you donât take the time to report it, you are actively hindering the softwareâs development.
You can report here : https://developer.blender.org/maniphest/task/edit/form/1/
Thanks for your participation !
1 Like