2866906 - Empty fields for Partner / Name when assigning an Employee in Sales Order

When assigning a "ZM - Employee Responsible" in a Sales / Purchase Order, the employee cannot be found or the Name is not filled accordingly. The same issue happens for the type "VE - Sales Employee" or the error "Personnel master record XXXXXXXX does not exist (Message number F2653)" appears when assigning a number.

SAP S/4 HANA OnPremise

IEMPLOYEE, VE03, SD_REPRESENTANT_GET_DATA, hrmr_rep, VPE1, Partner, Header, Function, Description, IDADTYPE, no values found, Personnel master record XXXXXXXX does not exist, Personnel master record, does not exist, Employee Responsible, Partner function, sales employee, emloyee respons, ER, PE, Partner Functions, i_personworkagreement, IPERSWKAGRMT, IWFPERSON, F2653  , KBA , CA-HR-S4-OP-BP , HCM Business Partner Integration , How To