Make sure you change the specified nozzle size in the printer’s settings (not just slicer settings). That matters for the stepper scaling.
Consider you are now extruding a larger volume of filament through a larger nozzle. The reduced amount neckdown from filament size, and larger volume of plastic to cool, means you also need to now print at a LOWER temperature than you would with a 0.4 nozzle, else the plastic will be too liquid and want to run out of the nozzle faster than the filament is pushing it. You also now have more plastic mass pushing against the surface tension, and the increase mass can also not solidify on the part surface fast enough and want to droop over the edge. Back it down to 230c, or even as low as 220c, as well as increase your part fan max speed. See if that improves things.