I was told that the "Taut_w" animation that I remade as a priority 5 for the legs and 3 for the arms (that animation plays when you walk while in "Taut" lock) deformed the shoulders. I wasn't aware of it because I made it with my own shape years ago, and I still have the same shoulder width so it slipped unnoticed through the tests.
There was no issue with the running animation ("TArun") but I remade it with the same two different priorities because it too moves the arms an could potentially break non-RR restraints, so to err on the same side, I updated it as well.
If you have updated your Vixen legs cuffs to v1.30 and notice your shoulders looking wrong after walking in chains, you might want to update them again, but this time no need to replace them. Simply go to Dark Wishes, click on the updater there while wearing your Vixen legs cuff, rez the orb you are given (don't use an older one) and start a soft update, meaning click on "UPDATE" instead of "REPLACE", wait a little and your two animations will be fixed. Please do not do this at any of the other three updaters, otherwise your Vixen cuffs would revert back to v1.29 (while staying mesh, hm, there's no magic involved) and your anims would not be fixed anyway.
Please note : For this hotfix, it is important to rez your cuff on
the ground to update it, do NOT do this while wearing it, the no-copy
animations will be rejected by SL and the original animations will
vanish, which will screw up the update since they won't be replaced
afterwards and you'll have to contact me.
By the way, if you had to relog to fix your shoulder width after it has been deformed by the cuffs, know that you do not have to anymore, there's a "Reset Skeleton" option in the context menu when your right-click on your avatar.
Have fun and sorry for the inconvenience,
PS : Thank you Lana (Ashlana20) for reporting this and for later confirming the fix worked.