When defining a Global Pipeline Library, the Retrieval method does not seem to be lazy loading or populating adjucts correctly.
This is most easily seen when initially selecting either Modern SCM or Legacy SCM:
Notice how all the child radio buttons are all pre-expanded.
The UI is also confusing as you have two sets of radio buttons and the Modern SCM child radios do not show any differentiation with the Legacy SCM sibling radio.
The fix may be as simple as to switch to a dropDownDescriptorSelector as that would lazy-load its content... though even there it may additionally be necessary to have the SCMs populated from another drop-down...
Care will be required to ensure that the lazy attribute is properly populated so that the required state is captured whatever solution is implemented