With FU1-40 set to linear, it should allow the V to go to maximum input at full frequency. If it were me, I would set FU1-40 to "Squared", that's how you save energy with a VFD, but that's a side issue, not what's causing you a headache right now.
Did you read DRV-10, the DC bus voltage? There is noting in the VFD that reads the actual line voltage, it doesn't really care actually. It just converts it to DC, so all it really needs is a high enough DC bus voltage to be able to create an RMS output voltage to match your motor. So where are you reading 360V from? DRV-11? That's the only valid place to read the output voltage. If you are reading it with a basic hand-held digital meter, the accuracy of that value is suspect unless it is a VERY expensive meter with the proper PWM and harmonic filtering capability necessary to read the output of a VFD. "True RMS meters" do really do a good enough job of that in most cases, partly because there is no real definition of what that means. It's more related to the price tag of the meter than anything else.
So I suspect that if you are reading it from a hand held meter, it's a worthless value. If you are reading 360V from DRV-11, then I would expect the value of DRV-10 (the DC bus) to be around 510VDC. If DRV-10 reads 580V, then I would expect DRV-11 to be 410VAC. By the way, if your input voltage is 410VAC, your output voltage cannot be more than 410VAC, there is no magic going on here that can create voltage that is not there...
So, IF you are reading only 510VDC on DV-10, yet your incoming line voltage is truly 410VAC, then what might be happening is that you have excessive DC bus ripple. That can be caused by a severe voltage imbalance on the AC input such as a phase loss, or it could mean you have capacitor failures taking place inside of the VFD. If your incoming voltage is balanced +-5%, then I'd suspect the DC bus caps are failing.
The iP5A drive line is over a decade old now, so if you bought it used or even if you bought it new, it's possible that you got hold of one that has been on the shelf somewhere for years. If so, the supplier should have warned you to perform a "capacitor reforming procedure" before fully energizing it the first time, otherwise you can damage the capacitors. DC bus capacitors need to be energized about once per year to keep from de-forming, a slow chemical change in which the oxide layers that form on the surface of the capacitor film dissolve (de-form) back into the electrolyte around them. Without that oxide layer, the film layers are just conductors so simply applying full power to them can cause holes to burn into the film layers and eventually lead to full failure. Prior to that full failure, one of the symptoms of it being on its way to the junk heap is that the DC bus ripple increases.
