These issues can easily be reproduced, just try to import this boxset from CDStub: http://test.musicbrainz.org/search?query=Marcel+Proust+Albertine+disparue&type=cdstub&limit=10 :
1. http://test.musicbrainz.org/release/add?artist=90c1a0cf-6822-46c7-8bc6-5a158e8a0d13
2. In the "Add disc" dialog, search CDStubs with title "Albertine disparue (lu par Denis Podalydès)" :

• The "Add disc" dialog/div has an absolute position: this can be irritating when you add a boxset because you had to go from bottom to top a few times (e.g. to check that the last disc you added were disc 5 and not 4, ...). At least in advanced mode, when the dialog closes, view is not moved to bottom of the page, so you've to got to bottom to add a new disc (since it's where the button is).

• In advanced tracklist mode, track length are not set when you add a disc

• When you add a new release, an empty disc 1 is already present. If you add a new disc from an existing tracklist/CDStub/FreeDb, it's added as disc 2 and so forth. So you have to manually remove the first disc. And if you do that at the beginning or after having added disc 1, further discs won't be added.

• At end you got a crash!
  Caught exception in MusicBrainz::Server::Controller::ReleaseEditor::Add->add "Attribute (name) does not pass the type constraint because: Validation failed for 'Str' with value undef at /home/musicbrainz/musicbrainz-server/script/../lib/MusicBrainz/Server/Edit/Medium/Edit.pm line 166
  MusicBrainz::Server::Edit::Medium::Edit::build_display_data('MusicBrainz::Server::Edit::Medium::Edit=HASH(0xdad2228)', 'HASH(0xcd962a0)') called at /home/musicbrainz/musicbrainz-server/script/../lib/MusicBrainz/Server/Data/Edit.pm line 457
  MusicBrainz::Server::Data::Edit::load_all('MusicBrainz::Server::Data::Edit=HASH(0x83d1480)', 'MusicBrainz::Server::Edit::ReleaseGroup::Create=HASH(0xdaa4bf8)', 'MusicBrainz::Server::Edit::Release::Create=HASH(0xdab4330)', 'MusicBrainz::Server::Edit::Medium::Create=HASH(0xdad1e50)', 'MusicBrainz::Server::Edit::Medium::Edit=HASH(0xdad2228)') called at /home/musicbrainz/musicbrainz-server/script/../lib/MusicBrainz/Server/Wizard/ReleaseEditor.pm line 596
  MusicBrainz::Server::Wizard::ReleaseEditor::create_common_edits('MusicBrainz::Server::Wizard::ReleaseEditor::Add=HASH(0xc37e630)', 'edit_note', undef, 'data', 'HASH(0xc5e5bf0)', 'create_edit', 'CODE(0xc6bf028)', 'previewing', 1) called at /home/musicbrainz/musicbrainz-server/script/../lib/MusicBrainz/Server/Wizard/ReleaseEditor.pm line 569
  MusicBrainz::Server::Wizard::ReleaseEditor::create_edits('MusicBrainz::Server::Wizard::ReleaseEditor::Add=HASH(0xc37e630)', 'data', 'HASH(0xc5e5bf0)', 'create_edit', 'CODE(0xc6bf028)', 'edit_note', undef, 'previewing', 1) called at /home/musicbrainz/perl5/lib/perl5/x86_64-linux-gnu-thread-multi/Moose/Meta/Method/Augmented.pm line 46
  MusicBrainz::Server::Wizard::ReleaseEditor::Add::create_edits('MusicBrainz::Server::Wizard::ReleaseEditor::Add=HASH(0xc37e630)', 'data', 'HASH(0xc5e5bf0)', 'create_edit', 'CODE(0xc6bf028)', 'edit_note', undef, 'previewing', 1) called at /home/musicbrainz/musicbrainz-server/script/../lib/MusicBrainz/Server/Wizard/ReleaseEditor.pm line 498
  MusicBrainz::Server::Wizard::ReleaseEditor::prepare_edits('MusicBrainz::Server::Wizard::ReleaseEditor::Add=HASH(0xc37e630)') called at /home/musicbrainz/musicbrainz-server/script/../lib/MusicBrainz/Server/Wizard/ReleaseEditor.pm line 79
  MusicBrainz::Server::Wizard::ReleaseEditor::_ANON_ called at /home/musicbrainz/musicbrainz-server/script/../lib/MusicBrainz/Server/Wizard.pm line 163
  MusicBrainz::Server::Wizard::navigate_to_page('MusicBrainz::Server::Wizard::ReleaseEditor::Add=HASH(0xc37e630)') called at /home/musicbrainz/musicbrainz-server/script/../lib/MusicBrainz/Server/Wizard.pm line 379
  MusicBrainz::Server::Wizard::_route('MusicBrainz::Server::Wizard::ReleaseEditor::Add=HASH(0xc37e630)', 'MusicBrainz::Server::Form::ReleaseEditor::Recordings=HASH(0xc...') called at /home/musicbrainz/musicbrainz-server/script/../lib/MusicBrainz/Server/Wizard.pm line 128
  MusicBrainz::Server::Wizard::process('MusicBrainz::Server::Wizard::ReleaseEditor::Add=HASH(0xc37e630)') called at /home/musicbrainz/musicbrainz-server/script/../lib/MusicBrainz/Server/Wizard/ReleaseEditor.pm line 88
  MusicBrainz::Server::Wizard::ReleaseEditor::run('MusicBrainz::Server::Wizard::ReleaseEditor::Add=HASH(0xc37e630)') called at /home/musicbrainz/musicbrainz-server/script/../lib/MusicBrainz/Server/Controller/ReleaseEditor/Add.pm line 23