Hi JanCK,
lets clear some things.
You have 4 basic rows of buttons on your keyboard that they can connect to each other in different ways.
STYLE (is related with the OTS)
OTS (is related to the left & right hand voices, the style and the multi pad)
MULTI PAD (is related only with the OTS)
&
REGISTRATIONS.(related to many things)
Left hand voices are connected with the style's OTS or whatever voices you have at the moment and not with the style itself.
(but regs need a style to save left hand voices...pif)
So when you save a style in the registration no 1 you also have "marked" the voices you choose at the moment to be at no 1 registration too.
In registrations 2-8 you have "unmarked" the style so when you change to reg no2
it doesn't change whatever style you play at that moment and it doesn't care at all what style is in reg no1 or reg no3 etc.
Whatever changes you make to a style using the style creator or just the mixing console should be kept in reg1.
Is there a chance you saved the original style to reg 1 and not the modified style?
Also remember that when you save something to registrations (style,voices) you should not remove it to another folder or change it's name.
Registration cannot find it anymore.
If a Reg is looking for a Mary Loo who lives in Boston and Mary changes her name or leave the town it doesn't know where or how to find her.
Same with the right hand voices.
Every change you make to them it should be kept in Reg as long the original voices don't be moved or renamed.
EditI will try to find a way how you can also save the left hand voices without changing the style in regs.