Hi,
In screenshot of Maintenance order, only plan cost is showing & no actual cost is there. So you are not getting any value in maintenance cost report as this report only shows actual cost (i.e. plan cost settled to WBS using KO88). Apart from this WBS budget report S_ALR_87013558 will show any amount if get consumed from this.
So you need to settle this plan cost then it will show you in maintenance cost report.
Regards
Shishir