I'm suspecting that this happens when there are statuses that don't exist in the workflow or vice versa.

SYSTEM NOTICE
Undefined index: 40

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Full path: C:\wamp\www\mantis\core\bug_api.php
Line: 882
Variable Value Type
p_bug_status 40 string
p_wanted_status 50 integer

t_status_enum_workflow
Variable Value Type
10 40:in development,90:closed string
80 10:new,40:in development,85:integration testing string
85 10:new,86:verified string
86 10:new,40:in development,90:closed string
90 10:new string
Filename Line Function Args
C:\wamp\www\mantis\core\html_api.php 1418 - - bug_check_workflow ( <string>'40', <integer>50 )
C:\wamp\www\mantis\core\html_api.php 1630 - - html_button_bug_assign_to ( <integer>25436 )
C:\wamp\www\mantis\bug_view_inc.php 689 - - html_buttons_view_bug_page ( <integer>25436 )
C:\wamp\www\mantis\view.php 34 - - include ( <string>'C:\wamp\www\mantis\bug_view_inc.php' )