Unable to change order which shows up as a demand in MRS planning board.

I have set up MRS for HR resource and have created resources and orders some of which have been assigned manually. However when I try to edit an un-assigned order I am lways getting an error message "Demand 000004000041 is already being processed by user aaaaaaaaaaa" where aaaaaaaa is my HR resource name.

I am using MRSS V2000 0003 SAPK-V2003INMRSS Multiresource Service Scheduling on a SAP HANA 1709 on premise edition.