Can't input two half maps into Validation (FSC) as described in "Local res. estimate with imported map error"

Hello, I am new to cryoSPARC and so please excuse me if this question has an obvious answer that I could not find!
I would like to run an FSC validation job and, after importing two half maps, I could drag the output of the first import job (i.e. J1.imported_volume.map_half_A) into the volume field of the Validation (FSC) job. Then, I tried importing J2.imported_volume.map_half_B following what was suggested in the topic “Local res. estimate with imported map error”. However, this did not replace one of the (identical) half maps A in the group 1 created in the previous step… but instead created a group 2 with again two identical half maps B.
What am I doing wrong?
Thanks and best regards,
Zorg