Multi value control never activate on public instance. I tested MultiSelect, DataMultiSelect and DataUUIDMultiSelect. Tools -> JCR Queries show the values never publish. All other controls works perfectly.

I use this code:
DataUUIDMultiSelect data = (DataUUIDMultiSelect) tab.addControl("dataUUIDMultiSelect", "heroes", "Heroes", "");
data.setConfig("tree", "data");
data.setConfig("repository", "data");

Can you add a multiselect control in the blossom sample module to test that everything works like it should.