Hello i have encountered this scenario if Steel Grade Main is Fe410 and Steel Grade is Fe250 ,the software does not design beam it gives an error as shown in the attachment.
but if steel grades are similar design is performed without an error.
iam attaching RCDC File for investigation.
Structure2-Beam-1-3.325 m.zip
?
This crash is not due to different steel grades used.
From the RCDC File you shared, looks like the levels you have grouped does not have the same beam geometry on all levels.
Could you check the beam geometry at 9.975m for beams I have marked in image below:
The beams I have marked in below image is not present on 9.975m level or else some data seems to be missing.
Please check at your end and let me know.
Try grouping just the 3.325m and 6.65m level only.