I equipped a four star, level 4 Divine Life shield on my Suwai Firstborn, and then selected "Upgrade to level 8"

I walked away for a bit and when I came back, I saw that it was still upgrading.  Thinking that was odd because going to level 8 shouldn't take very many tries, I looked and saw that the artifact still showed level 4. The upgrade "animation" was still going, and showing success nearly every time (as it's a high upgrade chance), and each try to upgrade was still taking silver away, but the level of the artifact is still level 4. I lost a lot of sliver this way :/

I can replicate this every time. Whether I choose  Upgrade 1 level, or upgrade to level 8 or 12, etc... I tried some Accuracy gauntlets also, and had the same effect.

I then tried this on another character to see if I could replicate. I tried to upgrade the helm from level 8, and choose "upgrade 1 level". It succeded twice, but did not upgrade the + level of the artifact to 10, so I cancelled, but then the helm level upgraded to 12 after I cancelled.