This is the same bug - except i notice you said "SQL Anywhere with SNC" i think you meant sql server? I was wrong that it was any numeric column, it is just the computes that show up as identity and they can be decimal types.
Also, the compute MUST be a numeric constant to reproduce the bug.
If it is a column or a compute from columns that does not cause the problem:
1 as test1 (identiy bug)
vs
vou_inv_amt - vou_paid_amt AS test1 (ok)