Semi-rounded buttons in the configuration selection modal when opened from the training process form

For mysterious reasons to be investigated, when it is opened from the training form, the buttons in the configuration modal are all weird because the

border-top-right-radius: 4px;
border-bottom-right-radius: 4px;

don't work, they're being overridden by

.field.has-addons .control:first-child:not(:only-child) .button

which sets them to 0.

EDIT: same thing in the model selection modal; I think it's related to how in this, and the worker version selection modal the ➕ button / USE button is not rounded and somehow that bit of CSS impacts the buttons in the modal footer too.