GPS Time Sync reverts after ~15 seconds

My watch has been behind by 10 seconds for as long as I can remember (I got the watch roughly 4 months ago). I finally decided to look into how to adjust this and found that it adjusts with GPS. I tried doing that and it synced perfectly, but later on I noticed it was back to being 10 seconds behind. So I tried again and paid attention, and at around 15 seconds after doing the sync, the time just "warps" right back to being 10 seconds behind, almost as if it defaults back to another configuration. I tried it multiple times and each time the same thing happened, always at around the 15 second mark.

Anyone experiencing this and know how I can fix this (without resorting to manual time adjustment)?