I’m sure @Michael will be able to give a better answer here, but I can at least say using a higher gauge wire (thinner) will work better.
A good explanation on why wire gauge matters is because the thinner a wire is the more resistance there will be to the flow of current and more resistance means more energy loss (check out this page for a bit more of an explanation). The energy loss in this case is in the form of heat from the Nichrome wire.
If the resistance in the wire is really low (lower gauge wire) then you will end up having a current flow too high for the supply like Michael mentioned, which will cause the overcurrent protection to kick in and drop the voltage.
I’m not 100% sure on what the correct gauge will be, but if you can find the Ohms/m rating on each gauge of Nichrome wire then reverse engineer it from there with the values you already know (Power and Length) I’m sure you can find something suitable!
Hope this helps.