When importing a submodel, why do my new elements turn inactive (gray color or disappear) and old elements change their attributes to the defaults in the new scenarios?
This will occur if your current scenario is one that did not exist in the model that the submodel was created from. Basically there is no way for the program to know which physical/topology information should be used for the new elements, in a scenario that was not present in the submodel. So, the default values are used for those new elements in those existing scenarios (the default value for "is active? is "false"). If you switch your active scenario to one from the submodel's original model, the submodel elements will become active, but then the elements from the original model will become inactive, for the same reason.
When importing a submodel, you should first make sure the structure (parent/child relationship/hierarchy) and labels for both the alternatives and scenarios match, between the source and destination model. Otherwise, the above difficulties will occur, due to the program creating new alternatives/scenarios. If all the scenario/alternative labels/structures match, then the program will know where to place all of the data (which is stored in the alternatives) from the submodel, so the physical/topology information will be present in your scenarios.
Pipes connecting to the wrong element after submodel import