Bug? Update cue is'nt possible when using submasters at <100%

No, quite right in theory. But a bulb at 20% never puts out half of the intensity of 40%. It's not a linear mathmatic science, but a visual perception of that moment.
And frankly i don't care on what value a fader is, or at what value I need to program it exactly. it's the visual picture that must match.
So a syntax that would set the lights in half of their output just wouldn't get the job done, it's never math, it's perception.

So the main question remains, and I wil start from scratch to try to explain.

On a complete empty desk I patch 5 dimmer channels
I program a show :

Q1 = 1 thru 5 full
Q2 = 5 @ 50%
As the show is in tracking, only spot 5 will go to 50%
Q3 = 1 thru 4 @ 80%
End of sequence

I make a submaster for channel 1 thru 4, inhibited, exclusive, and assign it to fader 1
[Goto Cue] [1] [Enter]
only ch 5 will go full on, as the fader is off.

fader at 100%
all lights will go on

[GO]
1-4 remain full
ch 5 goes to 50%

Now I think all of the frontlight ch 1-4 is too bright in this scene, so I lower submaster 1 a bit
frontlight goes to 68%.
Still, i think channel 4 is too bright in this scene, so I want to take that one more down
[4] {wheel down} [update] [enter]

now the desk says "can't update, cuelist empty"
* I don't want to update the submaster, as it is fine as it is now.
* the information of ch 4 is stored into cuelist 1, so there can't be an empty cuelist: the fact that the light is on means there was some sort of information of ch4 in the cuelist.
* Update should track back that particular channel in the cuelist, or give options in what cuelist the channel needs to be adjusted.
* I don't have time to type in a long syntax just to record a cue (the workaround now is
[4]
{wheeldown}
[update]
[nontrack]
[cue]
[433]
[part]
[2]
[enter]
, as I am in the middle of a show, and not having track of where exactly i'm in, and in what part some of the channels have been stored.
And then again, when I specify the exact location, all the sudden the "cuelist is empty" report isnt relevant anymore, and seem to be there anyway.

I haven't tried this specific situation, but something similar, so lets hope I got it right.
A small thing could be that in the original show where I encounter this problem I use several submasters with duplicate channels:
* ALL DIM submaster
* ALL front submaster
* ALL floor
* ect...

so ALL dim and ALL front have duplicates

Hope someone has a solution to this.

Cheers!