This morning I've tried make a new assembly of test, with 2 simple parts; each of them has been mesh separately inside of own part.
Results: while each part has been mesh correctly by the own mapped mesh tool, within the assembly the "sub tool of mapped mesh" doesn't work.
Appear a little yellow triangle near the command.
There is a manner that permit to you to "resume" the mapped mesh inside each parts? Some option. Or you must, always, make a giant mapped mesh in the main assembly?