Hi everyone, can someone offer me some advice please on left/right/top/bottom justification of ductwork/eccentric reducers when using fabrication parts?

I can achieve this using normal ductwork systems, however I cannot find an option when trying to recreate it using fabrication parts.

I have tried creating the fitting using the normal systems ductwork and then used the 'design to fabrication' feature and the reducer doesn't get created and I get the following error code .........

Screenshot attached.

"Not all parts were converted. Eccentric transitions and taps that have offsets from the center line are unsupported and cannot be converted".

Many thanks!