Steps to reproduce:

1. change config, Administration->General->Regular expressions,add BITS in expression ^(MMCSS|BITS|gupdate|SysmonLog|clr_optimization_v2.0.50727_32|clr_optimization_v4.0.30319_32)$
2. remove "BITS" service item  been auto discovered from hosts.

Result:
See screenshot attachment 1: Reports->Availability reports   the item data remains.

also See some error attachment 2:

Undefined offset: 0 [ in report2.php:436] 

when click in Reports->Availability report ->Service "BITS" (Background Intelligent Transfer...

a new error see screenshot  attachment 3:

Undefined offset: 0 [zabbix.php:21 → require_once() → ZBase->run() → ZBase->processRequest() → CController->run() → CControllerProblemView->doAction() in app/controllers/CControllerProblemView.php:257]