Constraints not working over linked solvers after undo

If I have two separate solvers, link them, I can successfully apply a constraint. If I however then undo that, any constraint I try to apply (besides the Attach) will fail with the “not part of the same solver error”.

Fresh scene example:

And this is it happening to my animation scene. As you can see, my character is flying off when using an Attach constraint (am I doing something wrong?), so I figure I could maybe get away with a weld constraint, but alas this issue! I would love to know if there is any weld constraint workaround for a file like this where I have already setup a good bit of stuff (Or if there is any guidance for attach constraint issues like this).

Using Ragdoll 2022.07.20

Not sure if this help…
On the first video I can see you have two solvers… try first doing merge of the solvers Ragdoll>Edit>mergesolvers

The second tip, I think Attach CNS could work better than weld…“could be” not necessary .

Second video:

It seems that your wrist Joint, has not marker. Attach CNS works between MARKERS. You could assign it and just turn on Kinematic ,

Missed this one! Thanks for reporting this, with your excellent video example I was able to reproduce this really obscure bug on my end and squash it!

The reason the Pin and Attach constraint wasn’t failing was because they weren’t checking for the same scene like Weld does. Although it should have! Because you have technically been able to Attach across two scenes, even though that isn’t physically possible. So the error would happen later instead. I fixed this as well

Both fixes will be part of the next release. :partying_face:

Hmm, it’s hard to tell from your example. It’s been a few days since this issue, have you uncovered any more clues? Alternatively, could you try making a new polyCube, assign a marker to it, and then Attach this to the crab? Does that work? I can’t see anything obviously wrong in your setup, it looks good.

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Fantastic to hear! Both that the fix is incoming and I’m not crazy.

As for the rider character setup, I ended up just importing the character into the crab rig scene, merged the solvers, and now everything seems to be working well.