The Apps are still there. No icons.
You USED to be able to go into Mac OS iTunes to rearrange your iPhone icons, but Apple removed that feature.
ONE FIX
Now you have to use an App called Apple Configurator 2, but that requires the most recent Mac OS, which isn’t compatible with my 2011 MacBook Air.
Apple broke this.
They need to fix it.
SECOND FIX
One way around this is to delete apps from your iPhone, power off, then power on the iPhone.
It took me three tries, but after I deleted enough apps, the missing icons came back.
Then I moved them back to my first page.
