QSS File Changing MainWindow size from Fullscreen to a small size

Quick question I have a QSS file that i use to set the style and this works great. However I seem to be getting a weird problem.

When I launch the program I tell it to start in fullscreen but instead the program launches as a small window the code is

Code:

---

GUIForm lGUIForm(aFullscreen, fOwner,aConfiguration);
 
    if (aFullscreen)
    {
        lGUIForm.showMaximized();
    }
    else
    {
        lGUIForm.show();
    }

---

Below is my stylesheet

Code:

---

QDialog
{
   background-color: #3A3A53;
   font-family: "DejaVu Sans";
}
 
#MAINFRM
{
   background-color: #3A3A53;
   font-family: "DejaVu Sans";
}
 
#HEADER
{
   background-color: rgb(12, 12, 40);
   color: rgb(255, 255, 255);
   font-family: "DejaVu Sans";
}
 
#MENUBAR
{
   background: qlineargradient(x1: 0, y1: 0, x2: 0, y2: 1, stop: 0 #ffffff, stop: 1 #c2c2d4);
}
 
#FILTERBAR
{
   background-color: rgb(58, 58, 83);
}
 
#VIDEOFRM
{
   background-color: rgb(0, 0, 0);
}
 
#ALARMBAR
{
    background-color: rgb(35, 35, 61);
    color: rgb(255, 255, 255);
}
 
 
#MSGBOX
{
   background-color: #141428;
   font-family: "DejaVu Sans";
   color: #D9D9EA;
   border: 0px solid #9595A9;
   padding: 0 10px 0 10px;
}
 
#IndicationPanel
{
   font-family: "DejaVu Sans" ;
   background-color: #3C3C79 ;
   border-color: #67677E ;
   color: #67677E ;
   border-style: solid ;
   border-width: 2px ;
   border-radius: 4px ;
}
 
QLabel
{
   background-color: #3A3A53;
   font-family: "DejaVu Sans";
   color: #D9D9EA;
}
 
QPushButton:hover:pressed{
  font-family: "DejaVu Sans";
   background-color: #3F3FB3 ;
   border-color: #F0F0FF ;
   color: #F0F0FF ;
   border-style: solid;
   border-width: 2px;
   border-radius: 4px;
 }
QPushButton:hover:!pressed {
   font-family: "DejaVu Sans";
   background-color: #D9D9EA ;
   border-color: #000000 ;
   color: #3A3A53 ;
   border-style: solid;
   border-width: 2px;
   border-radius: 4px;
}
QPushButton:!hover {
   font-family: "DejaVu Sans";
   background-color: #D9D9EA ;
   border-color: #000000 ;
   color: #3A3A3A ;
   border-style: solid;
   border-width: 2px;
   border-radius: 4px;
}
QPushButton:disabled{
   background-color: #9595A9;
   border-color: #67677E;
   color: #67677E;
   font-family: "DejaVu Sans";
   border-style: solid;
}
QPushButton:disabled:pressed{
  background-color: #3C3C79;
   border-color: #67677E;
   color: #67677E;
   font-family: "DejaVu Sans";
   border-style: solid;
}

---

The weird thing is I know it’s to do with the stylesheet as if i stop it from being loaded the program launches in fullscreen. Has anyone seen this or have any solution how to solve this that would be great.