I found a workaround if we are partitioning on a clustered index which is a not the PK (i don't remember it working with the PK)
create clustered index IX_P_Tab_col on Tab(col)
with (drop_existing = on)
on [primary]
Note: simply dropping the clustered index doesn't move the table, you need to recreate it on the target FG for the table to move...