The cause was a missed case from #130440 where `use_nla_remapping = true` was being unconditionally passed to `fcurve_to_keylist()` rather than determining the value with `ANIM_nla_mapping_allowed()` as it should have been. The fix is simply to use `ANIM_nla_mapping_allowed()` instead of unconditionally passing `true`. This PR also changes an outdated comment to properly explain why `adt` was null in the first place (which is precisely to catch bugs like this). Pull Request: https://projects.blender.org/blender/blender/pulls/147957