Estimated hours are not updated in Redmine

[ghost]

Estimated hours are never set in redmine. Neither when creating a new task nor updating an existing one. I don't know if the problem is on redmine mylyn connector or on eclipse redmine mylyn plugin side.
Log on server side (REDMINE_INSTALL_DIR/log/production.log) does not show a value by estimated_hours:
Processing by IssuesController#update as XML
Parameters: {"issue"=>{"subject"=>"foo", "description"=>"bar", "tracker_id"=>"2", "project_id"=>"11", "status_id"=>"1", "priority_id"=>"2", "start_date"=>"2015-07-30", "due_date"=>"", "done_ratio"=>"0", "estimated_hours"=>"", "category_id"=>"", "assigned_to_id"=>"3", "fixed_version_id"=>"", "parent_issue_id"=>"", "notes"=>"", "watcher_user_ids"=>nil, "custom_field_values"=>{"1"=>"", "2"=>"", "6"=>""}}, "key"=>"2259a47a6b3my-secret-key-216bfea575", "id"=>"3040"}

Environment:
eclipse luna 4.4.2 (Win7)
mylyn plugin from @ljader (https://github.com/ljader/redmine-mylyn-plugin)

Redmine 3.0.4
redmine mylyn connector 2.8.2 (from @joaopedrotaveira github.com/joaopedrotaveira/redmine_mylyn_connector because this fork fixes the Updating attributes failed problem (#57))
ruby 2.1.6p336 (2015-04-13 revision 50298) [i386-linux-gnu]
Rails 4.2.3

Issue on redmine_mylyn_connector: danmunn/redmine_mylyn_connector#45