I have also experienced this sometimes with my stealth.
When it is new, it tends to be difficult to get on and remains a tight fit for a number of days during which I cannot wear it for too long, and eventually it will stretch out and become more comfortable to put on and keep on all day.
I have tried various bands to try and keep the silicone ring from slipping back and find that it is inconsistent. mostly the ring will slip back as you describe above, where there is a little frenulum skin exposed which will begin to swell the longer it stays like that, or if I somehow manage to keep that in place along the underside, then the top side of my glans will have compression marks where the ring is trying to pull it back in.
Is it possible to have a design where the ring is inline with the corona as well as a straight join with the stealth fabric?
sort of like this:
