This was fixed in one of the service packs in 2020 R1 already ? Recently did training on 2020 R2 and we used continuation graphics without problems.
Can you check if it reproduces for one of the default styles ? Might be style or model related.
happens in all styles and various models.
It's listed as being addressed in the 2020R1 HF1 readme.
doesnt appear to have been fixed.
see attached pics using ootb isogen style. Cont graphics set from 0 to 3 in order