I am sorry for the troubles. Are you sending the watch face to the device from the ConnectIQ store again or responding to an update notice in Garmin Express? Is the watch face showing up in the Manage Apps section in Garmin Express? Also, the maximum number of apps is 16 so make sure the 920XT has fewer apps installed. If all other items are syncing successfully then I suggest you contact Product Support by phone or contact the developer of the watch face to inquire about any known issues with it.
I went via Garmin Express to Connect IQ store and got the watch face into Garmin Express, it says it's downloaded to the watch but when I remove the watch from the cable it hasn't, it's still just the default face.
It happens with any watch face I've tried (including trying to put either of the two I was using previously back on)
I'm not sure it's had anything else to sync via Garmin Express (activites/steps sync via bluetooth to my phone fine)
I would be happy to help you with this. Once the watch face is sent to the watch you have to use the menus on the watch to select it. Please see the FAQ below.
How do I enable a Connect IQ item on my compatible device?https://support.garmin.com/support/searchSupport/case.faces?caseId={46e93d80-05ad-11e5-78eb-000000000000}
I did it through the mobile app in the end. Worked without doing any of that stuff, but useful for future express attempts! Weird that it didn't need it the first couple of times I downloaded faces via express.