Hello
Did you check if the planned order/requisition generated by MRP was for stock transfer? Can you please provide a screenshot?
It is possible to make a stock transfer not relevant to MRP using a BAdI and maybe this BAdI is implemented on your system. Take a look on the following blog for details:
Making an element not relevant to MRP or MD04 using BAdI MD_CHANGE_MRP_DATA
BR
Caetano