Why do operations involving a dump from the booster result in an error with the new multi-target option?

Using, for example, any of the demos/examples (e.g. this) of the new multi-target feature, when trying to do anything involving the dump from the booster results in an error:

reg.fit(X, y, eval_set=[(X, y)])
booster = reg.get_booster()

XGBoostError: [10:40:24] [C:\buildkite-agent\builds\buildkite-windows-cpu-autoscaling-group-i-0750514818a16474a-1\xgboost\xgboost-ci-windows\src\tree\tree_model.cc:740](file:///C:/buildkite-agent/builds/buildkite-windows-cpu-autoscaling-group-i-0750514818a16474a-1/xgboost/xgboost-ci-windows/src/tree/tree_model.cc:740): Check failed: !IsMultiTarget():

Is there any way around this or is it just because the feature is still experimental?