The following changes should solve the problem.
diff --git a/app/helpers/issues_helper.rb b/app/helpers/issues_helper.rb
index e1e0fc559b..f71eb13b23 100644
--- a/app/helpers/issues_helper.rb
+++ b/app/helpers/issues_helper.rb
@@ -129,8 +129,8 @@ module IssuesHelper
content_tag('td', check_box_tag("ids[]", other_issue.id, false, :id => nil), :class => 'checkbox') +
content_tag('td', relation.to_s(@issue) {|other| link_to_issue(other, :project => Setting.cross_project_issue_relations?)}.html_safe, :class => 'subject', :style => 'width: 50%') +
content_tag('td', other_issue.status, :class => 'status') +
- content_tag('td', other_issue.start_date, :class => 'start_date') +
- content_tag('td', other_issue.due_date, :class => 'due_date') +
+ content_tag('td', format_date(other_issue.start_date), :class => 'start_date') +
+ content_tag('td', format_date(other_issue.due_date), :class => 'due_date') +
content_tag('td', other_issue.disabled_core_fields.include?('done_ratio') ? '' : progress_bar(other_issue.done_ratio), :class=> 'done_ratio') +
content_tag('td', buttons, :class => 'buttons'),
:id => "relation-#{relation.id}",